As long as you fit the specs of the contact (most circle lenses/costume lenses sold are an 8.6 and a bit wider than average, and USUALLY they only sell plano but you can get lucky and find prescription sometimes) you ought to be fine; just check that it's a reputable brand they're selling. I bought my dollyeye lenses (also available at pinky paradise and dollyeye.com and are lenses with a good reputation/good reviews) from the dealer's room at Anime north since I was lucky enough that they also had prescription contacts for sale.
However, I don't recommend getting contacts from the DR if you've never, ever worn them before; like everyone here will say, make sure you get an exam and fitting to make sure you can wear contacts and you know how to properly take care of them and put them in and out. Cosplay contacts are also in general less comfy than regular prescription contacts, since they're usually thicker and aren't custom-fitted to your base curve and diameter, and that can take some getting used to even if you normally wear regular contacts. (Also, most recommend soaking new contacts for a few hours- some brands have a REALLY strong solution that really burns your eyes and needs to be soaked out before putting them on.)
Originally Posted by Moofingham
There is a vibe here that says "We're in this together! Through thick and thin fabric! Through cold water washes and burning hot irons! Though we might super glue ourselves to our projects, cut holes/gashes/oh-god-mom's-gonna-kill-me into the dining room table, we will stand strong together. Unless there is a 75% off sale at the Fabric store. Then you're on your own. And get the hell out of my way." <3