$20?? Man you got a good deal on flats. Chromes are like at least $30 after tax and/or shipping and thomastiks are ridiculously expensive. Not to mention the setup a lot of guys ending having to do if switching from rounds and/or lower tension.
TI flats are expensive, yes, but they last forever. I have them on my walnut P Special (installed 2002), my EBMM Sterling fretless (installed 2002) and my 30th Anniversary EBMM Stingray (installed 2006). Other than an initial truss rod tweak to account for the lower tension, I've done zero maintenance and all three sets are going strong.