I have built the House of Evil, and my Bad Dream House is in progress (so already paid for). I have not yet purchased the Burns Monster or the Heck House (each 300 treats). I currently have 127 treats. When I started the Bad Dream House this morning, it left me with just a few treats left (around 14, I think?). It's been around 8 hours and I've picked up over 100 treats. Admittedly, that was waking hours, but still... Even if that's just 150 treats a day, it should be 4 days for both of the remaining things I can purchase with treats. I have not spent any donuts on the Halloween stuff, so do not have the mausoleum, nor the ray gun.
As joeyransdell suggested, visit other springfields. You can get treats and TP/eggs (which can lead to more treats) from their cemeteries, etc. You also get treats if their House of Evil is ready and you touch it. I don't *think* this should prevent them from getting treats from it (please someone tell me if I'm wrong). As a result, visiting people who have also advanced in the Halloween quests, but haven't been to their Springfield for a while, seems to be the most productive, treat-wise.
