One of the least expensive scout setups would be to buy an SKS and use a scout type rail available. Those who have love the results. There has been some development of a rear receiver peep site for the SKS, so that might complete the scout profile.
I've also considered a scout type setup on my G3, but that's not a traditional scout platform and is far over a typical scout weight.
If you already like a scout setup you like on another rifle and have a BAR that serves you well, a custom scout scope mount may be worth your while.