Whats do you think is the Average cost of Commissioning A CS map?

Hi! I've been working on a passion project in gmod and have been getting off and on commissions from here to help out with work and Ive been throwing around the idea of getting a map commissioned from the ground up for this Project. Generally we've used Pre existing maps and they work with varying degrees of success. The one Map comm I have gotten so far was an complete redo of a bomb site of a pre existing CS:S map, and that was about 300.

So the question I have for any map makers, How much would it cost to get a whole CS map from Nothing to something, as well as how much it might cost if some of the Map assets could be taken from other maps, such as props, or layout features recycled?

While I doubt I have the Budget for it at the moment, this is just an idea I'd like to sit and think on.

Thanks!

Bonus Question, what would be the best way to translate my ideas into usable map references? I was using Minecraft for the last one but that didnt work out super well and led to a lot of communication issues, thanks!