Cheapest is not the best. First couple of things would be to read up on your preferred model and then the makes that carry them. Do more reading here on why one model is better than the other. I picked the Systema PTW M4A1 2010 after much reading.
Get AV right away so the community can help you and have access to more info. You have to be patient with AV as it takes between 1 to 4 weeks. Hopefully your intereat does not fizzle then. Good luck.
What you want and what you can get are 2 different things...