Update: the dream is on hold. I was quoted £250ish for the whole work. I then asked about just converting the security board, and I'm still waiting for a response.
I take it that includes burning all of the 40+ roms? Honestly, it sounds about right. It takes literally hours to burn them, and then there's the cost of the chips.
If you're interested in doing the leg work yourself, invest in an eprom programmer. You need one that can do 42 pin chips. There's a thread for programmers here:
Best, low cost, programmer for most arcade hobbyists to have???
Then just start burning the mame set for the game. The game will boot without a security board. When you're at that point and you have "working game" you can ask either for a converted security board or decrypted program roms (just four chips).