I've been known to roll with...well, I roll like Diggumup.
If I am going to a train show, I will generally go loaded for bear. I probably wouldn't leave the house for garage sales unless I had $200 in cash, bare minimum.
If going to an estate sale, I treat it like a train show. I still haven't broken the $1,000 mark in the amount that I've spent at an estate sale, but I've come close many, many times.
You know what is funny, though? When I pre-plan, go to the bank for cash, and have all my ducks in a row, and then think I am going to spend all of it, I typically can't find anything worth buying. Three weeks ago, I went to a train show with $800 in cash, the checkbook, and debit cards, and found absolutely nothing to buy!!! Not even one thing!
When I am running late, in rag-tag fashion, and feel woefully underfunded, there are usually tons and tons of scores to be had. More than once in my life, I've had to call for back up, generally my wife or dad, and ask for them to bring me $--- so I can pay for the stuff that I've found.