I'd be interested in one for a .45 Compact USP. Where can I find one if they exist?
Also, where would be a good place to get quality night sights for it for cheap? (can this be a do-it-yourself thing?)
Yes, try here:
As for night sights, I like my Heinie sights. They are about $125 or so. Many people like Mepro night sights. You can get those from AZ Gun Runners. You can Heinies at:
Here are mine on my Tactical (keep in mind they are taller than normal sights to accomodate a suppressor):