The Russian BTR covers a wide range of vehicles and quite a few are used in Alcovia. BTR-152, BTR-60/70/80, and BTR-50 are all used in Alcovia in one capacity or another. The models for these vehicles seem to be harder to track down than tanks. In this category it seems that plastic kits rule. There are a couple of gaming models and diecast toys. In each category I'll be addressing the basic vehicle as well as variants that I know of. I have decided to forgo posting pics of models and box art here as they will show up fine with a little Google-fu.
BTR-152
ICM (plastic kit)
This company seems to be the only one doing the BTR-152 as a 1/72 plastic kit but does a couple of BTR-152s including an open-topped, covered and command post versions. These models generally fall into the $10-15 range when I have found them online.
BTR-60/70/80
Trumpeter (plastic kit)
Trumpeter does a BTR-80 only. Online shopping searches put this in the $15 range. This is the only 8-wheeled BTR that they do.
ICM (plastic kit)
ICM does two versions of the BTR-60 both an APC and command version. These models, like most of their kits falls into the $10-15 range.
ACE (plastic kit)
ACE models has had a lot of BTR-60s in its inventory but like a lot of their models they can be hard to find. In fact, their website shows all their BTR-60 models are OOP but you can still track them down here and there. These models generally fall into the $15+ range.
Easy Model (diecast)
Easy models does a good BTR-80 in a couple of color schemes but these things fall into the $15-20 range. Why this is, I am not sure.
Liberation Miniatures (20mm gaming)
Sold through RH Models, Liberation offers the BTR-60, 70, and 80 in a variety of models. Unfortunately a good number of them are out of stock (not OOP), though it does seem that RH tends to bring things back in stock as they are able to. It is also worth noting that they also have a BTR-80A remote control 30mm turret by itself which would be perfect for updating Alcovia's older BTR-60/70s. They run about $13 depending on exchange rate. The turret is $4.
BTR-50
ACE (plastic kit)
ACE does two models, standard APC and command. Being ACE models, it is no surprise that they are out of stock, but you can still find them floating around online for $10-15.
Liberation Miniatures (20mm Gaming)
Liberation does have a BTR-50 APC in its inventory though it is currently listed as out of stock. There is no price listed but I imagine it would fall someplace around the $15+ range based on RH's other prices for the Liberation Vehicles.
The pickings on BTRs seem very thin, I must say. With half of the offering out there either OOP or out of stock, I may have to consider some other vehicle options. I will also note that while I was looking around, I did come across some vehicles that had slipped my mind while I was arranging the forces of Alcovia and a few that I'd not heard of before.