TRMS does cost more to make. Today the prices between TRMS and just RMS are not much different but in the old days it's a big thing. Also the price difference reflect 2 different lines of products. The 115 is made in Malaysia.
Thanks for the reply. I was trying to gauge which might be the better value for a electronic hobbyist. The main pull of the 15B I think would be the mA setting. But I'm curious how much that would practically matter for a hobbyist, seeing as mA can still be measured on the 115 with a bit more error. The 115 DCA setting says 1% + 3 digits for error (with .001 resolution), so if you were measuring a 100mA circuit on the 115, then you should get a measurement between 96mA and 104mA. I think for hobby purposes, that's plenty accurate. Correct me if I'm wrong.
You're not wrong. The problem with the current measurements in 115 is not that much the precision (that's OK), but the missing ranges. If you need to measure, say, 3mA, you are in the margin of error on the lowest 6.000A range (the meter can display anything between -0.003 and +0.003 with no current at all...). Not to mention the nonexistent sub-mA ranges...
The 110-117 series is intended for electricians and very specific jobs. Each model in that series is missing something that other model has. Want to do general repairs around the house? 115 is great, until your stove or freezer go south, because you can't measure temperatures. You need 116 for that, but that come with no current capabilities (beside the uA range to measure the flame sensor current - that model is targeted to HVAC technicians). 117 gives you back the Amps capability and throw in no-contact contact voltage detection but takes back the temperature and the uA range. There is no such a thing as a "fully featured" model in that series. It's a great meter though, smaller than 15B+, fits nicely in one hand, you can operate the rotary dial with the same hand you hold it. Seems nicer built than 15B+, but that might be just an impression. Has a bar graph the 15B+ series is missing, which updates at a higher rate (10x or so) than the numerical display - great for signalling fast changes the display can't keep up with. Also, 117 has a min/max/average function 15B+ is missing.
The 15B+ series seems more appropriate for all-around work (including electronics) to me (17B+/18B+ are more featured - include a relative mode and temperature/LED testing, respectively).
I have access to 116 and 15B+, 17B+ and 18B+, in case you have specific questions.