Normal ketones are 0. There should not be ketones. It sounds like your vet tested for ketones and there were some? I'm not sure what to make of that if they didn't mention it to you as a problem, only I would guess that's a relatively low level, but I don't really know.
Ketones are very dangerous and can get worse quickly - the combo that you mentioned of not eating well and having an infection worries me - those, combined with too little insulin, are the setup for ketones and DKA. You want to nip the ketones in the bud before you reach a DKA state, which is an emergency situation that requires vet care, is very expensive, and I believe has a relatively low survival rate.
Don't mean to overly scare you, just want to be sure if you do see ketones you get that treated. Good catch Lori on bringing that topic up!
Yes, dental problems can cause higher BGs.
Here is a link to finding a store that carries EVO:
http://www.evopet.com/where-to-buy/. The other ones that are lower carb are the ones the vets sell - d/m and MD. I don't know what the carbs are on Wellness. Those 3 (EVO, d/m, MD) were the lowest carb last I checked, which is now a couple years ago.
I believe there is something in the Sticky up top on where you can buy insulin cheaper. Some places are more like $90, but I think the shipping costs are steep so I'm not sure how much savings it is. You can also check the Supply Closet forum - might be someone with a used vial they are looking to sell there, probably would be quite a bit cheaper, it really varies.