1 shop 10 niches vs 10shops with 1 niche each?

You could do a combination of both. You could have your niche specific sites all named similarly. For instance, "CrilleShoes," "CrilleShades," and "CrilleBags" (obviously all terrible examples). You could do targeted marketing, and have a targeted product selection for each. However, they're all part of the "CrilleShops" brand. So, there would be a natural continuity that would allow you to logically and organically link them together into your "CrilleShops" network, essentially creating that larger shop you speak of. Now you can still do more highly targeted, niche specific advertising, while giving the customer you'd targeted with advertising for your sunglasses shop the opportunity to buy some sweet shoes and a hand bag while they're at it.

I may have had a few beers, and ecom really isn't my game, so there may very well be some technical (or other) problems with my strategy...but I do think it's fairly sound.

Depends on if your niches are somewhat related. If yes, you can make one shop, if not it would look weird if you sell cars and socks at one place (as an example).

Customer base!

It's not so much about the niche as about the customer base. Are the niches relevant to the same customer base?

If they are completely unrelated then obviously separate sites will almost certainly deliver you much better targeting, conversion and profit. However if all/some are aimed at the same customer base, and if you are building a list for that customer base, then you may find it works better to combine.

It's a tough call and not as clear cut as some might suggest.

Good luck with your venture.

"Strength in numbers" "don't put all of your eggs in one basket" "the more the merrier" and you get the point by now lol.Also you have a greater chance of getting better google results breaking things down as much as possible,if you wanna let the customer of shop "x" know about what you sell on shop "y" just make a partner sites/related sites tab somewhere on your websites and list them all.Plus if you're planning on doing this for a long term life decision I'm pretty sure you'd honestly feel ALOT safer with multiple sites generating say $20k a month all together than trusting to make a life around one site making $20k by itself with no backup options.Not to mention the fact you even brought up the term affiliate DEFINITELY should mean you're gonna break theses sites down as much as possible,maybe even not put the affiliate products on some of your sites in general.I can't speak from experience but from what I've researched google can be a real pain to people who have affiliate links on their sites(now I'm not sure if you're gonna have your affiliate products camo'd as regular ecommerce marketplace products with the "buy now" button holding the link but I still don't know if google can key that out or not)

If the "niches" can be placed in relevant categories so that the shop products are all consistent and somewhat related, fine, but otherwise I would use a shop for each niche.

Is not money issue? how you can say is not about money? sales is about money.If you focus is sales you generate more money