I'm in the same boat. Heading there in March/April, and don't like spending all that money at a room salon (although they're really fun to go to). Although the RLD is cheap (like $70 for a quick fuck), their service isn't great, and I'd rather pay double the price for real GFE, rather than the standard make you cum as fast as you can, that you get at the RLD...
If anyone has any good spots, please share. I heard Banpo (near Kangnam station has a few good ones)...