From: someone
Originally posted by Aynen Kuroda I own 1024 sq. meters of land and I reach my prim limit easilly with just one floor, to do 3 floors on 512 sq. meters is, well... troublesome 
That's about the biggest understatement I can make.
but if you insist I'm sure it CAN be done, it won't be fancy though. Where naysayers see the impossible I see a challenge

Xedeus, I think your dream of a home/shop on a 512 plot CAN be done, and further I'll bet you can pull it off for a couple of hundred lindens with a little planning and legwork.
Here is one way, just off the top of my head:
Lets assume you have 100 prims..
Get yourself a low prim house that you find *livable*. Not trying to plug, but I know people are finding the 27 prim beachouse fairly popular -- its fully moddable and costs $1
(no typo - $1). Sits on a 10 x 20 base that fits well on a 512 plot... and high ceilings.
With 2 doors and adding a prim to make the 'loft area' a full floor you'd be at 30 prims.
Rip out one of the walls with windows and clean that to use as your shop 'entrance' - use the saved prims to make a 'store entrance' and you'll probably still be hovering around a count of 30.
You want living space -- challenge yourself to keep your personal furniture to 20 prims... you CAN do it. Jodie runs a low prims store with LOTS of great stuff.. I make a 2 prim leather sofa and a few other things.
So far we have 50 prims left..
So how do we put up your goods? VENDORS. Jonquille Noir uses a 1 prim vendor - I believe its Moopfs..
you would run out of space before you ran out of vendors

One for each 'catagory' of item.. lets say you set up 10
still got 40 prims left -- still good for decorating your store and having a few items on 'display'
Have fun, enjoy, and take the road less travelled.
If you need any help, feel free to IM me in world (If you can find me

Siggy.