Best bet is on one of the Internet auctions. There are very few HOB designs at Outerzone. HOB contacted them to remove plans due to copyright. Some have been waiting for them to start reproducing kits again, but that has yet to happen, although it would be welcomed.

If you do a search on E-Bay, there is one NOS (New but Old Stock) ME-109, but it is $130 + $30 shipping. At $160 + $13 tax = $176 is a bit out of my price range.

EBay: Vintage House of Balsa Me-109 1/12 Stand Off Scale Anniversary Release