I found an older 12" Delta on Craigslist for $100. The guy had owned it for a number of years, and never even changed the blades once - so it didn't have a lot of use. I figured it was hard to go wrong for that price.
I found a great video series on YouTube showing the full tear-down and rebuild of the planer, plus blade replacements and a feed table upgrade by ghostses:
After replacing the blades, which was fairly easy with the blade jig I bought for $20 on ebay, I decided to build a feed table.
I built it out of HDO plywood - High Density Overlay - which is smooth, durable and makes a great surface for sliding material over. I mounted the planer to a simple cart make of 2x4's, OSB, and MDF cut-offs.
It's a very straightforward design: a sheet of material bolted to the in-feed and out-feed tables on the planer.
The idea of the feed-table is that it supports the stock enough to get rid of snipe at the end of the board. It did reduce it, but I still get a little bit. The way I deal with it is to run boards through the planer continuously, and run a final scrap piece at the end that gets the snipe.
I'm probably going to add a fold-up table at the end, so long boards don't fall to the ground after being planed.
All said, the feed table is worth the time to install. The stock ends up being smoother and flatter, and it's easier to manage the lumber coming out the back.