Well, if all you want to do is play them on a VGA monitor, then you'll be able to find VGA boxes for sale.
But none of them will take advantage of the GC Digital Out port, so in effect, you'll just be watching composite analog quality on a VGA monitor.
If you truly want to take advantage of the Gamecube's progressive scan games, this is the only way I know about.
I saw some HK website selling it completely modded already for $54.