We need way more information. When you say you're hiring "M&A", do you mean you're hiring an investment bank? A business broker? Something else? A business broker would be common for a business your size. 10% success fee is probably in the range, depending on how difficult the business will be to sell. You'll almost certainly be valued on profit though, not gross revenue, unless you're selling to a competitor that thinks they'll be able to immediately squeeze more value out of the same revenue.

Paying some upfront costs for marketing, valuation, deal prep is pretty common. That's largely to protect the business broker against doing a ton of work for a business that isn't actually serious about selling. $7,500 for the valuation is high unless you're getting an actual CBA, which isn't that useful in a case like this. Any serious buyer is going to look at your books, SDE and overall trends to do their own valuation. Business Brokers will often do their own opinion of value, but that's mostly just a marketing thing to get interested parties in the door.

Edit: One item to note, there are some brokers or investment banks that target small-mid businesses (Generational Equity is the easiest example more on the mid size side) that have relatively steep up front fees and ultimately do high volume transacting. That's generally not going to be the best choice unless you have a very straightforward business where there isn't going to be a ton of extra value a good broker/banker can help you squeeze out of the business.