From: VirtualVisitor Vyceratops
Huh?
Sorry, not a financial trader here.
That was for Sling's benefit

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Although the explanation below would make more sense if you understood how the LindeX works and you wouldn't have to operate on blind faith.
From: someone
Just want to spend US$100 "one time" and get the most L$ for my money.
Where should I buy this?
The biggest thing to remember is that every time you buy L$ 30 cents gets added as a transaction fee.
For that it doesn't really mean that you have to spend US$100, it simply means that the US$ amount you buy L$ for should be relatively big compared to 30 cents.
Practical example:
- you buy $100 worth of LL in one go so you pay the transaction fee once: $0.30
- you spend the $100 in 4 goes (so $25 each) so you pay it 4 times: $1.20
- you spend the $100 in 10 goes ($10 each) so you pay it 10 times: $3
Whether or not that difference matters to you is your decision. Some people prefer to not how too much L$ at any given time because they feel they'll get too tempted to spend it all at once so in that case it might make sense for them to put up with more "wasted" money in transaction fees by making smaller L$ purchases multiple times.
Did that make sense?
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I'd personally prefer if you got a basic sense of how it works rather than me just giving you a step-by-step though. It's your money after all, and you should know *why* you might want to do things differently from the way you are now. The explanation will be a bit vague, if only not to dump too much on you all at once.
Let's say you're on a veggie market and trying to sell lettuce. If you want to get rid of them ASAP then you'll accept anyone who wants to pay you the current going price for them. But if you wait a bit longer you might get a better price for them. I hope that sort of made sense?
It's the same way when you buy L$:
1) you can do what you likely are doing now which is called a "market buy" which technically means "give me my L$ at the best rate I can get right now this very instant"
2) or you can set a rate at which you want to buy L$ in which case you're waiting for someone selling their L$ in a "give me my US$ at the best rate I can get right now this very instant"
Take a peek at
https://secondlife.com/my/lindex/buy.php and scroll down a bit until you see two columns with descending/ascending values.
For practical purposes (and for simplicity's sake) only the very first line of both matters and then only the left column of each.
Let's look at the left one first (I only copy/pasted the left value to keep things a bit simpler):
From: someone
Open Sell Orders at the Best 20 Rates
Exchange Rate
L$260 / US$1.00
It represents "limit sells" or in other words: people who placed a sell order stating that they want to get $1 for every L$260 they're selling.
If you buy inside the viewer, or - by default - on the site then that's the column your order will be processed from so in this case if you bought L$ (which is a "market buy"

you'd be getting L$260 for every $1.
Looking at the right column:
From: someone
Open Buy Orders at the Best 20 Rates
Exchange Rate
L$269 / US$1.00
This is the column that's really the reverse of the other one.
If people want their US$ *now this very instant* they'll do a "market sell" and get $1 for every L$269 they're selling.
You'll notice that the exchange rate is L$9 / US$1 higher than the other rate. There's a reason for that but I think things are probably complicated enough already

.
Now: if you really want that extra few L$ per US then what you'd basically do is put a "limit sell" order and then wait for someone who is in a rush (or doesn't know better) to sell so they'll be paying your - worse for them, better for you - rate.
One last thing to remember is that "limit sell" orders are filled from low to high so for every "rush sell" (aka market sell) the lowest number in the right column counts. And per number (exchange rate) the person who first placed an order at that rate is served first.
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Practical steps:
you only have to do this one one time:
https://secondlife.com/my/lindex/currency_settings.php and set it to "Advanced" and click "OK"
From "My Account" on the main site, left side of the page, the "Linden Exchange" click "Manage" so the extra options slide out:
1) "Increase Credit" - this will let you deposit US$ onto your account with a $25 minimum
2) Click the "Buy L$" that is *below* "Manage your L$" on the panel which takes you back to the "two column exchange rate" page
You now want "Buy at a Specific Rate (Limit Buy)". Scroll down and look at the "Open Buy Orders" (the column on the rate). The rate you want to "limit buy" for will be L$1 below the lowest rate listed there which is at the time I write this "L$269 / US$1.00".
So in "Exchange Rate in L$ / US$1.00" you fill in: 268
The reason for picking one lower than the lowest is so that your order will be ahead of everyone else's which significantly cuts down on the wait time (otherwise you could be waiting for your L$ for a week until the rest clears out). I tend to get my limit buys filled within 5-10 minutes at the most that way, usually it's near-instant.
Instead of filling in a US$ value you have to type in a L$ value so if you want $100 worth exactly just start with 100 x 268 = 26800 and adjust it until the number below says $100.00

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Then just click the "Offer to Buy" and go from there.
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Is it worth all the gibberish above? For your $100 worth you'd get L$26719 instead of the L$25922 you'd normally get; or L$797 more (or about 3.5%)
The only one who knows whether or not it's worth all that is you so

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But please, if you want to give it a go, make sure you understood everything I said: this isn't easy so don't worry if something didn't make sense. Just ask and someone will clarify it for you

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Or try it with a relatively small amount of US$ so you're not worrying about what happens if you get it wrong.