Hi James,
I think that if you travelled with a budget/backpackers frame of mind you could do soooo much cheaply. Looking at the temples etc takes a bit of time and isn't that expensive.

If you use trains/buses where ever possible you will save a lot. It is only about 120bt ex Bangkok to Pattaya. Round about the same to Kanchanaburi which is great to see. Accommodation here is also cheap.
Another must see if you are interested in temples/ruins is Aytthaya? I really loved this and it can also be reached by bus cheaply.
When eating, try to stay out of the main tourist areas and food is really cheap. Buy beers from the 7/11's or supermarkets when not sitting in a bar.

Best thing to do is research your trip. Start with accommodation, what you want to see/do and work from there. If you explore alot yourself instead of taking tours you will save a fortune.

Depending when you want to leave in November, just keep in mind that places fill up quick nearing Xmas so don't leave booking til the last minute.

Karin