I think it is not a big payment to obtain it all in one package. At least, time costs money too, you know
If I were to use any of these chips (Since am not psychic and can not read the errata two years in advance - I will not), I would, of course, buy these boards, 50% off or not. The original poster has not indicated whether amateur, small run or large volume. If amateur, the toolset for SILabs is a true bargain, if professional the thousands for ICE, dev board etc does not matter much.

I do not think we can conclude this till we hear more from the original poster as to WHAT, WHY, not just where to buy?

Erik