Removing this is one of the simplest things you can do. Remove the interior, plastic "sail panel". It's the triangular-shaped piece on the opposite side of the door than the mirror. It "pops" off - just pry it carefully. Once you do, you'll see 3 nuts to remove and the wire to disconnect.
I do not have any experience with that company you linked to. At $30, my gut tells my to "pass". I replaced my OEM mirrors, but I went with larger, power-slide outs.
How much are they through the dealer? Another place to check (for quality parts) is LMC Truck.
1998 K2500 Suburban 6.5L TD 3.73 rear, Ron Schoolcraft 18:1, Kennedy ECM & IC, Timing gears, Splayed main caps, 3.5" Kennedy Exhuast/No Cat, K&N Filter, Boost/Tranny Temp/EGT(Pre Turbo), Ceramic-coated Manifolds, 195 Stat's, 265/75's (VSSB Adjusted) 7,000lbs (on a scale) Remote Mount Oil Filter, Remote Oil Pressure Sensor