Sounds like the fuzzy still has his anal sacs. Exotics vet usually charge around forty dollars for the office/check up fee. Surgery prices can range from $100-$500, depending on the vet in your area. Look for a vet who sees a great deal of ferts and who has done this surgery a lot (usually it's cheaper when the vet does a majority of the same surgeries). Remember, too, though, that descenting your fert isn't mandatory. Leaving the glands intact will not harm him; however, you might want to see if he is unaltered, as well. Neutering is considerable (especially in pet ferts), because it helps reduce aggression/frustration within your fuzzbutt (although there aren't the health risks associated with unaltered males as here is with unspayed females. It's primarily behavior that is affected beside hobs).
Answers: First, check your ferret for any tattoos. The most common are two bluish-black dots on the right ear (from Marshall Farms) and these would indicate that your ferret has be neutered and descented. Other breeders tattoo in other areas or use different shapes; some (like Path Valley) don't do any tattoos, but their ferrets are still neuter and descented. Even though he smells bad when excited, that doesn't necessarily mean he hasn't been descented - I spot when I take mine to the vets they tend to smell stronger, but they are all descented (I own two Marshall's and two Path Valley). They have scent glands all over their body which they can secrete oil from even if they have been descented (which is the removal of the anal scent glands only). As for the surgery, prices are going to differ from vet to vet, I think mine charges around $200-$300. It's at least going to be a couple hundred. Personally, if you find out your ferret isn't descented, I would freshly let him be. This procedure is illegal in several countries external the US because it's considered to be cruel and unnecessary, and I agree with that. Descenting can sometimes do more harm than good, particularly if the vet doesn't have a lot of experience next to this procedure. All this procedure does is prevent your ferret from "farting" (expelling a poof of odor, like a skunk) when frightened or excited, it has little effect on their over-all odor. If you find out your ferret isn't neutered, consequently you might want to have this done, as this can help cut back on the smell (unneutered males are the smelliest of adjectives ferrets). Neutering would also probably run around a couple hundred.