campershell locks

I have a 92 Ranger with one of the older campershells on it with the 2 T-handles on each side and the locks in the middle. It was on it when I bought the truck several months ago, but had no key for it. I had a key made for it (by the code on the locks), and it fits, and the tumblers in it are good as its turning, however the locks itself are messed up and it won't lock. I am looking for a cheap (no more than $25) to be able to secure the shell from being opened. I checked with the local camper shell dealers/truck accessory places in the area and new locks will run about $40 each. The locks are quite rusty, and I put PB Blaster(similar to WD-40 as it will loosen things up froze in place by rust, and actually does alot better of a job) and it won't even do no good. I tried it because the locksmith and one the shell dealers recommended using WD-40 in the lock to see if it would do any good. Does anyone have any ideas of how I can secure my campershell to keep anyone from getting in it, while doing it cheaply?