I got mine from Books a Million a few years back; I think it's x16? Never had a reason to look elsewhere.
Cpm9ball is correct IMO, but if you want something smaller for shows or such, you want an triplet ( 3 pieces of glass) apochromatic ( to get rid of color fringes from lighting) thus making it easier to tell if real doubling or fake images on the edges. The magnification can be anywhere from 5-6 to 16X, depending on what you most commonly look for in a coin. I use a 10X which is a compromise. I can recommend this one, although there are others at different pricing. https://www.amazon.com/BelOMO-Triplet-Magnifier-Attached-Anti-Reflection/dp/B000EHLU8U Jim
Magnifier choices depend on what you are looking for on the coins. 16x is awfully strong if you are looking at whole coins but OK if you like tiny flyspecks. I get a lot of good out of a pair of Dollar Tree $1 +3.25 diopter 'reading glasses' (the strongest diopter they have). You can pay more elsewhere and get +6 diopter. They allow seeing in 3D which shows things that you miss squinting with one eye. You will look 'funny' wearing them over your prescription glasses and finding the pair that fits your needs just right may require standing there and trying on several. They sell singly in stores but by the case online. https://www.dollartree.com/wire-rimmed-reading-glasses-with-a-325-diopter/255297
I bought a set of lupes from harbor freight that is what I use. https://www.harborfreight.com/5-piece-loupe-set-98722.html
Three years ago, Santa put this is my stocking. It is made by Mobius and has three different power lenses that easily snap on or off. Best part is two high power LED lamps that shed light on the coin you are magnifying. Less than twenty bucks from Amazon. I own many lenses but this is the one I always reach for.
The Harris 10x loupe has been with me for 40+ years. https://www.wizardcoinsupply.com/pr...fFuEuz1Q0_crRSzBZIZ5JdDhmUUDGcTgaAoImEALw_wcB
For use at home, I recommend an enlarger lens rather than a loupe. They are far better corrected than ANY loupe and are cheaper for better quality.
Try this... It is branded IMagnify now and comes with four lenses. https://www.amazon.com/gp/aw/s//ref=mw_dp_a_s?ie=UTF8&k=iMagniphy
