Security & Possibility Question (I think o.O)

I have a couple of questions that might seem a bit stupid. I've been working on a specific script using a database for days now, when it occurred to me I might be making this very complicated for no reason at all.

I am intending to make a no-modify/no-transfer item with a single script inside.

What I would like to make this script do is keep a running tally of two numbers: 1. the running total spent on products made by a certain creator (when the Pay button is used) and 2. the running total of products the person has bought from this creator.

For example, when you equip the object, floating text will display 2 numbers: 1 being the total number of purchases you've made, and 2 being the total value of all of the purchases you've made.

Now, I know that some tip jar scripts work somewhat similarly (as far as keeping a running total of how much money has been tipped). So I'm wondering if I could possibly reverse-engineer that concept into how much money you've given a specific person and how many objects you've bought from that person. Would that be possible?

I also know that in order to keep the string from resetting itself, the on_rez { llResetScript(); } function will probably need to be removed. Would this possibly pose a security issue?

I'm sorry if this is confusing. Please feel free to ask me questions if I can make it any clearer.

Any feedback would be appreciated. Thanks!

- R

Edit: I plan on using a variety of security checks (password, creator name for the script & the object it's in, etc) and the internal SL email commands to talk between scripts. Does that sound feasible? Or would that be one of those annoying things that wouldn't work because the UUIDs will reset every time the objects containing the scripts are rezzed?

Would it be more possible to use a listen channel to talk between the scripts? Or would that just pose too much a security risk? Basically, I'd love to avoid using a PHP/MySQL combination here if I can. >.<

how exactly do you intend to detect the amounts paid to other users? because within LSL the only way a manual payment could be recorded is for a manual entry to be made.

Actually, I think I just did a bad job of explaining, but no matter. I've figured out a better way and will develop on that idea instead. Thanks!