Welcome to the boards.
Re-discovering is so much fun although it can dent the wallet.
Definitely stay on the hunt for an MP10. He's a glorious figure in all his forms and well worth the investment. I'm sure in time you'll find a collector on these boards who might have one to let go at a reasonable price. You'll definitely get a better deal here than through places like eBay.
I have a high end fake MP10 (ironic terminology I know) I use to educate people with and I can assure you he is inferior by far to the real versions despite aesthetically having more detail on him. He's a huge regret purchase for me. I was in the same situation as you contemplating what to get, which is why I made the mistake of getting the fake. I'll never make that mistake again which is why I wanted to share my experience with you. I now have several MP10's and they are all great fun both visually and for playability, especially when you add another Masterpiece figure or 2 into the mix.
I hope you enjoy your time here. There are bunch of great people on these boards - incredibly knowledgable and great guys to chat to.