That sounds fine to me...certainly it means the right thing, even if it may not be the most common way to describe it in a non-financial context.
Instead of "ask" you can use "offer price." Both of these may also be called "reservation prices." If you use that, you will also have to specify which one you are referring to. For example, "the seller's reservation price was X, which exceeded the buyer's reservation price by 10%." If there are not a lot of service providers, you can just call the seller's side the "price" and the buyer's side the "reservation price."
The right jargon kind of depends on who the audience is. If you are talking to economists, any of the terms I mentioned will be natural.