Tile over wood floors

[Mike Waltman]

The hardwood in my rental rehab is not worth refinishing because of some areas of dead wood so I've decided to go with tile. I picked out a nicer tile $.99 vs $.70 because I had it in the budget. Neither me or my project manager realized you cannot tile directly over hardwood and need to pUT something in between. 

The best he's coming up with is hardy backer that costs $9 per sheet and is putting me further our from budget and making me regret going with the nicer tile.

Anyone know any other materials or methods that could make this more cost effective?