I have a shower that is tiled, and the base is cracked and leaking, and needs to be replaced. I would love to put a one piece base in, but the shower is an odd size, and to get one custom made is out of my price range. Not sure what to do- replace the old tile with new tile(never done tile work before) or just what... Is there a resin based product that you can use to pour over the cracked tile to fix it?

I do not know if there is a quick fix. I have always heard that a leaky tile shower had the pan and floor replaced in tile.

I just recently learned how to tile. I tiled my entire shower and bathroom. Its easier than it sounds. HomeDepot.com has a nice "know how" section which may help you if you decide to re-tile. I would just re-tile it to avoid any future issues. The tiles may be a bit cheaper than a custom shower base.

Your shower has a shower pan with a flange type shower drain. This shower drain has weep holes that allow water that leaks through the tile and mortar to go back down the drain. Sometimes the tile man will allow mortar to block these holes. Where is it leaking from? Doug nailed it when he advised you to install a new shower pan and go from there. If the drain doesn't leak I would keep it. Good luck, Tom