instead of buying 100+ traps, this season, replace the springs or 4 coil em and then buy a doz or 2 new traps that will replace your weakest traps. my bro and i like to replace bout a doz or so traps each year. with the old uns, we take em out of commission and do some serious work to em. we replace the springs, add the 4coil kit, and other minor adjustments. we then have traps that function like our new ones we just bought.
we have been doing this for years, and each year we are able to extend out line with new and better( the old ones) traps.
just my 2 cents