It is always a good idea to check online at popular auction web sites to see what used copies of a lens (or other item) are selling for, to see if what you've found is a good deal or not. The most well known auction site allows you to do some filtering that can be really helpful. I looked at each version of EF-S 18-135mm, N. America only and "sold" items for actual selling prices, rather than asking prices. It was easy to search for the USM or STM version, simply by specifying those versions. To search for the non-USM/STM version on that particular website, just put a minus sign in front of any word you want to exclude. In this case "-USM" and "-STM" search terms brought back only that earliest version of the lens.
Latest and greatest USM versions in working condition are selling for as little as $112 to $240. A couple very low priced ones seemed like outliers... under-priced "Buy It Now" (seller error) or just bad luck auctions.
The optically identical, but not quite as fast focusing STM version appear to be selling for between $120 to $180.
The oldest version with slower, noisier micro motor focus ([not STM or USM) and a tad bit lower image quality, in working condition are selling for roughly $85 to $180 incl. shipping.
In all three versions there were some offered for a bit more that included accessories such as lens hood, filters, etc.
Of course, you also might want to visit some of the retailer web sites to see what the items sell for used and new. The EF-S 18-135mm IS USM lens new costs $599. The STM version new costs $100 less. The non-USM/STM version appears to no longer be available new... at least not anywhere I could find. Several of the retailers have used copies of all three versions. I'll leave it to you to visit those, if you wish.
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Alan Myers
San Jose, Calif., USA
"Walk softly and carry a big lens."
GEAR: 5DII, 7DII (x2), 7D(x2), EOS M5, some other cameras, various lenses & accessories
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