Heard the Rega 3 and have seen the Rega 6 in the flesh. The 3 sounded good. I could never wrap my head around spending that kind of money on that type of build quality. I know others disagree but I am not the only one. I don't think you will go wrong sound wise either way.
I have heard the VPI Scout, Classis, Prime and Aires.
If I were you I would skip over the scout and buy a used Classic or Prime. I think it will save you money as
it will eliminate the desire to upgrade for a long time and possibly forever.
Both can be had for under you max amount if you are aggressive