You're very fortunate to have found an affordable Vet who you're happy with
In my last post I should've specifically said that it's a good idea to look for trusted recommendations
from other guinea pig owners. There are always exceptions to every rule, of course, but it's a good idea to be wary.
It's worth bearing in mind that cheap treatment could end up costing a lot more, in the long run (in terms of subsequent treatment), if not carried out to the correct standard in the first place. Yes, things can go wrong even with the most skilled/experienced Vets, but I'd look to minimise those risks as much as possible by choosing a suitably qualified Vet.
Something else worth considering, in the case of neutering ops, is to clarify exactly what is included in the price quoted. I could be wrong but I think some places include a post-op check up in the cost of a neuter but I'm not sure all do.