I am into both although right now I have more maxi than minis. The color drives the price. The most common coloration pink/green usually run $20. The solid red mini runs about $200. have seen private parties selling for slightly less. Maxi minis on the other hand... most common color is green, these can go for anywhere from $40-$100. More exotic colors can run $250 OUCH! It comes down to what are you willing to pay? I keep my eyes open and snatch up the ones I can afford at any given time LOL.
There are a couple online stores selling them now too. Even thought mini and maxi minis are increasing in avaliability, I don't see the price comming down any time soon unfortunately.
The advantage to owning these is that thay can be manually propigated with minimal loss, a very good thing don't you think?