So really you should have said " my mate stocks - X, Y, AND Z" systems which would be best, no?
Theres no point in people recommending anything if your mate doesn't stock it?
£80 sounds a little low for a system, surely you'll need at least two units, one up and one down stairs?
If your mate imports and supplies these things, surely he should be your go to guy.
Have you gotten a list of what he has that's within your budget?
If so, what has he got?
If not, wait until he gives you a list, then post and people can give you informed opinions.
If hes an importer, there is no way he needs to wait until black Friday to give you a deal, his cost price is his cost price, regardless of this week or next!