Hey bud, if you find any info on higher No. Buffalo's let me know, Im fighting to find anything on my No.571
The price thing can always be tricky to answer unless its WAY off, mostly its up to your need/want/affordability. If its brand new still in box sounds great to me but I would still try to get it down a bit 250 could be a good deal for a mint blower but I have never purchased any "mint" blacksmithing tools lol!!
As for too much air? I dont see that as a problem, you can easily adjust the flow by adding a damper to the air intake of the blower itself, or if its hand crank, crank slower!
With fire control yea that can come with time, but it sounds to me like your not giving yourself enough coal to create the coke-ing effect and burning nothing but green coal~
Best of luck!