Riva:
Does it bother you that no reputable dealer sells these?
Nope.
The WS2803's smaller variant the WS2801 is used in many a pixel addressable RGB LED strips so is not necessarily a hobby device. As for 'reputable dealer', I'm no longer prepared to pay there 'reputable' prices if I can help it. My first 2x MAX7219 chips from Mouser cost more than 10x 'Buy It Now' MAX7219 chips from a 'eBay Top-rated seller'. My first obligatory Arduino clock project would have been about 25%-30% cheaper if I had thought to use eBay first.
The TLC5940 is a good chip but for me it's a bit more expensive (from eBay) compared to the WS2803 and the 18 outs of the WS2803 suit better for RGB LED's compared to the 16 on the TLC5940.
I said you should buy chips that reputable dealers will stock, not necessarily from the dealers themselves. I avail myself of eBay all the time, but on supported chips! Here is where I got 50 MAX7219s, they all work fine:
I bought my TLC5940s from an eBay dealer (hitechtools) for $3 each including shipping.
I'd rather use those chips than the one you mention just beacuse of the broadness of support available for them. Lots of people around here can troubleshoot and offer advice on these devices.