Been doing the same. However i have had real difficulty finding very good to fine copies of Dr No, Spy and even OHMSS.
2-3 years ago Dr No firsts were quite common on Ebay and not overly expensive, sometimes multiple copies were for sale at the same time. The last year they have been much rarer.
Any book giving you particular heartache Qwerty?
Noticed that about Doctor No too.
I'm not concentrating on the early ones because I absolutely do not have the money for them. I'll agree that finding a nice first of On Her Majesty's Secret Service was difficult for a while because that seems to be the cutoff when it comes to Fleming and book prices--everything before it seems to be extremely pricey while the three that follow are still relatively easy to get.
Currently trying to finish off the UK 1st paperbacks. Only a few more to go there and thankfully the always high priced and somewhat elusive Moonraker is starting to show up a bit more.