It's really important to know how your insurance handles prosthesis coverage.  I've had several health insurers since my surgery, and each has handled payments for prostheses differently.  Right now, I pay 100% of the prosthesis until my deductible is met, but the cost goes towards my deductible.  I find that I need a new one every two or three years (I can't figure out why they wear out, but they do!), so I try to time my purchase for years when I've met my $1,000 deductible.

If your insurance has a local shop that specializes in working with breast cancer patients on the list of acceptable places, I recommend trying there.  I've found the fitters in those type places more knowledgeable, and they tend to have a better stock of bras and forms.  They have a homey atmosphere that makes the shopping experience more pleasant.