Depends on your personal preferences. Personally, I'm not picky. I just want a cheap domain. LuckyRegister offers the cheapest prices compared to top competitors such as GoDaddy.
Depends on the domain name as such. Number of letters, number of words and dictionary words are some of the important factors that determine a domain's worth.
Assuming you mean a new registration? Then I would pay $9 inc Paypal processing fees. Anything else would be too expensive, and anything less.. would look suspicious, and would need checking out thoroughly before considering.
if you are asking a regular price to purchase one, $0 at hosting24 if you have a .com domain you can get from $200-$12,000 at flippa.com
That definitely depends. Most .COM domains I would not buy at all for any price. Some .COM domains would be a bargain for tens of thousands of dollars.
Depends, usually $7.95 or less Google coupons for GoDaddy and NameCheap and sometimes you can find short $4.99 or even $.99 specials. Cheers!