Hello - nice to hear from you again.
At first glance, $2,100 does seem high to remove a small tumor. But, it also depends on what that all includes - is that just the anesthetic and surgery? If so, then it seems very high. If there are many other things that they are also going to do, it just depends on what those things are (i.e. bloodwork, X-rays, MRI, cancer staging, histopathology, IV fluids, antibiotics, pain medication, hospitalization, etc.) A surgery performed by a surgical specialist will also cost more than your regular veterinarian doing the surgery. So, I would find out exactly what is all included in the $2,100 price tag. On a side note -- is this a surgery your regular veterinarian could perform? If so, you may save some $$'s. If not, then you may need to have a specialist perform the surgery. As far as staying overnight, that can vary from clinic to clinic. Specialist clinics typically like to keep pets overnight after a surgery, so they can be observed and treated all night long, to keep any pain under control, and they would contact you if Milo was having any problems. This is just quite typical for a referral clinic after a surgery. It is probably the best way to do things, but most of us in daytime clinics send most surgery pets home before the end of the day, as long as there is not a strict medical reason for them to remain in the hospital (IV fluids, etc.) So, what the referral clinic is doing is not wrong, it's actually a good thing - they just want to make sure Milo is getting proper and the best care possible. Although, I do understand about him being at home, in his regular environment, especially if he's a dog that gets stressed out when being away from home - sometimes in a situation like that it can actually be best to have the pet at home, where they can remain as calm as possible. I would definitely have a frank discussion with the referral clinic (if they do the surgery) about Milo's stress when being away from home, and also about the cost of the surgery. If for some reason you are not comfortable with what they are doing, you may have the option of having your regular veterinarian perform the surgery, or you may be able to go to a different referral clinic.
I hope this helps. Have a good weekend!