I have a question about foundations (i.e. box spring), for latex mattresses.  Right now I am looking at purchasing a new latex mattress and our current bed frame needs a box spring to work correctly.  Right now my options are:

1. Buy a new platform bed frame and make sure slats are 2 inches or less apart (I might have to buy slats separatly) - Expensive
2. Use current box springs (not recommended since they are old and also might not breathe well) - Free but may not work effectively
3. Buy a foundation from the retailer like Flobeds or SleepEz or other - price varies
4. Buy a foundation somewhere else (does anybody know of a good place to buy foundations?, eg. ikea?)

I've looked at a few places and there is somewhat of a price difference.  I don't think it matters as long as it works.  Even the color of the cloth is not important (I have a bed skirt).

Just wondering your opinons on this:

1. Can I use an existing box spring?
2. Why such a large price difference between some retailers for box springs?  Is one better than the other?  Is cheap OK?
3. How about Euro Slats - is it worth it if I combine with a thinner mattress?
4. Anybody know where to get a cheap foundation that works?
5. Anybody have plans to build your own?
6. Any opinions on the "best" bang for your buck for a foundation?

Probably a weird question but I am trying to gather information on each of the components for my purchase (mattress, mattress cover, and foundation).  I just want to get it right so I don't have to deal with returns but also not buy more than I need.

Thanks in advance.