I bought my 05 wrx wagon from stohlman last june. I have to say it was pretty painless. I looked on their website and found basically exactly what I wanted listed with an extremely good price. I called them to ask if there were any caveats to that price and they said it was a fixed no-haggle price. (21,7 for new wrx wagon w/the auto dimming mirror and all weather floor mats if you're interested)
Anyway, I have the same question as dFunk. How mod friendly are they?