I personally have no minimum number. It really depends on what you are planning to do with the domain and your time frame. For strict domaining, without development and a short time frame, you will obviously need to aim high, maybe 74,000 +.
I have been successful developing domains that had little or no exact match searches at the time I bought them. I sold one name with no development at all, and search volume less than 1000, within two months after I bought it. In other cases, I have bought names with low search volume and they have proven to be completely worthless. Some names and niches have not been discovered yet and if your in no big hurry to sell and have a knack for picking trends can be great investments. It's wide open, each name is unique.
Search trends are dynamic, start watching Google Trends to get an idea of upcoming searches.
There are many factors that make a good name. I would personally rather buy a name that gets 33,000 searches but is in a competitive niche with tons of products/services, than a name getting twice as much in a niche that is not marketable. A chess strategy domain is not worth as much as a debt consolidation domain regardless of search volume.
over 100 and I only have 110 domains. that said, its really none of your business #1 and #2 I was simply giving him advice I received from another well repected domainer. So please "C" your way out
1M+ exact-match .mobi domains, perhaps? Just going by your prior NP transactions.
Many of the domains you own appear to be 3 & 4 fig. exact-match .COMs.
I'd say commercial domains with even 500-1000 exact monthly searches can make solid foundations for development. As Valerie said, it depends on the niche and advertiser density.
I own a few in the 74,000+ range, half dozen or so out of around 160 total.
The fun thing about domains is they are all unique, and the skies the limit with regard to how you use them.
My latest buying has been focused (for development) on names that contain two prime keywords so that I can get the built in SEO benefit on two keywords.
For example,
Take two keywords with decent volume:
online coupons
coupons codes
combine them together and buy the name even if its low volume.
online coupons codes
With 'online coupons codes' I can optimize and build links for both keywords and stand a decent chance of getting some google luv for two high volume keywords.
For strict domaining though I stick with higher volume names. You can't easily explain something like this to an end user.