how much do baby oscars cost?

That is like asking how much does a puppy cost.

There isn't a uniform price for a baby Oscar. The shop will ask what it wants. I recently bought seven red Oscars at 2 1/2 inches and paid £8.50 each for them. Another shop in the area sell them for £5.50. Put it this way, the shop really shouldn't be charging you any more than £10, around $20 for a normal tiger, red, albino etc oscar that is under 3 inches. That's my opinion anyway

The price of oscars varies from shop to shop and from size to size. Around here in Hemel Hempstead Herts the cheapest I have seen is 2 for £8 i.e. £4 each for a 1 inch to 1 1/2 inch. Generally once they get to about 8 inches around £20 is a good price. Some shops charge more. The most I have seen a full size oscar for sale is £40(dont often see full size ones for sale). The thing about larger oscars is that they tend to be returns so the shop charges what they think they can get. One shop round my way prices them well and never seems to have them hanging around. Another shop sells them for more and thus has a tank with lots of big oscars in.

A thing to think about with buying bigger oscars is they get returned for many reasons. Could be the owner bought several to get a breeding pair, or perhaps they outgrew there tank (possibly kept in poor water conditions). Or it could be because the oscar was too aggressive(not good if you want tank mates). My advice would be to buy them small and grow them on. Its fun to watch them grow and they grow quick

Basically everywhere around me (Davenport, IA) they are $10.99.