how much would you pay for...

Not over 150.00 bucks myself.

A friend of mine was gonna pay 500.00 for a bottle of ref-v 50cc liquid.

I stopped him and the guy admitted he paid like 150.00 for it.

I seen on price lists usually 60.00 to 90.00.

I never bought that but know its pretty cheap on black market, local is different

If you know a farmer who has horses can get very very cheap, its not expensive as the quality is not that good I hear, but can't say cause i always steered away from it.

Some pay lots when they don't have access to a good source.

I seen guys pay $25.00 for 1 omona amps locally!
That all depends on if you are talking gym prices, international prices,or domestic prices. Gym prices are usually 200$-250$. International or domestic sources are much cheaper. It all comes down to weather or not you want to find a source and take the risk of ordering yourself or weather you are paying someone to take that risk.