Cheaper guns tend to have lower quality sensors that are cheaper
usually they have a wider sampling area, lower effective range and wider tolerances. That one looks to have a 12:1 ratio so at 12" away the sample area is 1" diameter. This means you can hold it further away and still get a good reading. Some of the cheaper ones have a much smaller D:S ratio (mine is 1:1 so at 12" away it's sampling a 12" circle!). It looks like it is accurate up to 900+F, my cheep one tops out at 122f. You get what you pay for, for the most part.
If you do want to return it check the specs of the one you want to buy and see if it's what you want.