Hubpages vs buying a domain

Hello all,

This is my first post. I stumbled across affiliate marketing by accident a few days ago and I have done nothing but read this forum since.

I read a thread last night that I can't seem to find now where someone describes how they make a hubpage(another thing I only just discovered) with niche keywords in it to test the water. I am hoping someone can answer a few questions for me.

I'm trying to learn all the lingo so bare with me while I try and ask my questions!

I have spent all day thinking of what my first venture could be and I have come up with a 4 word phrase, it is a niche market and the product isn't even on sale yet.

I check in google keywords tool and it says that monthly search is 170, no bar for competition and Avg.CPC is 0.04.

So I am assuming those statistics are pretty rubbish, but should I expect that for a product not yet released?

Should I go and buy a domain name in the style this-is-the-name.co.uk or should I make a hubpage up first?

Another problem is that I can't seem to find anyone that sells this product who is part of an affiliate marketing scheme, should I still go ahead and hope that I can find one later when the product arrives?

The product is low costing £50 so with what I can see the average commission is about 5%, that's not a lot of money unless I get a lot of traffic.

These are probably all obvious questions but I find that when I am reading the posts a lot of people expect a certain level of knowledge and I'm not sure of some of the basics.

Thanks