New domain or subdomains

Hi everybody. I have one question about amazon or alibaba(never mind) affiliate site.
I plan to create about 20 affiliate sites. is it okay to use one general niche domain with subdomains with niches?
for example: hotdeals.xxx>toys.hotdeals.xxx>games.hotdeals.xxx

in this case I will save money, but will google index subdomains too?
What is better, new domain for every niche, or subdomains, will it work with subdomains ?

Sorry for bad English.

I mean on Google indexing. Will it work ?

better use new domain for each or create a mega-niche site covering them all