i got a 10 dollar picatinny rail off of ebay, but the fit was not exact and i had to file it a bit to make it work. it is solid now though.
you can do a quick google search for them and come up with a ton of results.
i would advise you get one that is not the cheapest like i did. instead of the 10 dollar one maybe go in the 20-40 dollar range.
after that you can get a cheap but usable long eye relief scope for around 50 bucks with rings included. that will get you an inexpensive scout scope setup.
i prefer the one that sits farther back over the receiver myself, but if you do that type you have to alter the bolt handle or get a new bolt body altogether, which is a little cost prohibitive for this gun.
like you said the rifle itself is so cheap you don't want to go too crazy on the scope setup.
and the scout scope setup, although a little weird to shoot through for me personally, is pretty accurate once you get it dialed in.