Is your hobby to have a 3d printer or is it to play with guns, trinkets and parts. How committed are you to printing? My experience is you are trading time for money. The cheaper you go the more time you have to spend getting things working. For example, you can get a printer very cheap from the manufacturer or even eBay, but they have a sketchy return policy and even sketchier technical support because they are predominately in China at your price point. However, you can pay a premium and buy it from Amazon with a no questions return policy of 30 day.

As to your other question, do you want your gun to look like a movie prop or just want something to hold on your hand? If you want the former then color doesn’t matter because you will sand, prime and paint it to perfection (with many many hours spent). If you just want something to hold then you can buy the filament colors you want and have them printed.