As ccosby stated, if your not wanting to buy a HK94 to convert to an MP5, then the best route by far, but almost just as expensive unless you do yourself is buying the demil kit for $1500-$2200 depending on what you want and $200 for a receiver flat. The only way to save money that way is to do yourself but you have to have a great deal of knowledge of how they work and know how to TIG weld. Alot of people think that because they can build an AK from a flat that they can do an MP5. It's a whole different animal thats for sure as i've done my own and it was extremely technical and i still spent close to $2500 in parts when all said and done. You also got to factor in the supplies to refinish like sand blasting, parkerizing and then picking up the correct paint to use in which I went with the semi-gloss HK Black from Duracoat.