I don't know nuthin' about prices. I've been building and truing my own wheels for 30 years, so I have no frame of reference for pricing.

That said- you should be able to get by with one broken spoke by loosening the opposite side. However, if you break another spoke you should get the wheel to the bike shop ASAP. Multiple spoke breakage is a sign of spoke fatigue- once a couple go, several more are probably close.