Unlocked iPhone 4S with T-Mobile SIM from Straight Talk?

I want to get an iPhone and use it on Straight Talk's network. If I get an unlocked iPhone and get a T-Mobile SIM from Straight Talk (I understand I'll have to cut it down from a regular size to a micro size), will it work on the network? Obviously I don't want to invest $500+ in this and it won't work.

Sounds like you really need to call straight talk to see if this is a waste of money or not then.

Yes it will work as long as its unlocked