If you have higher buy ins for the foreign tournaments you might gain a few people attracted by the higher prize fund - but then you"d lose one or two people who couldn"t justify spending out money on travel, accommodation and the (higher) tournament fee.
The overseas APAT's are primarily full of local players, I don"t see why the effect it has on a tiny minority of the field should affect the buy in for them.
NB. putting the buy in up and increasing the satellites won"t balance out, if people are used to buying in direct they won"t switch to trying to win a satellite - they just won"t play. It would definitely put off players new to APAT if there was that perceived extra barrier on top of the higher buy in.
Putting the buy in up to £150 would completely change the tour, it would just be the same (albeit better structure) as so much else available.
Putting the buy in up to £100 wouldn"t have to change the demographics of who enters (and reduce the demand significantly) - but it probably would. Paying a £100 to enter a single tournament is a psychological hurdle that a lot of players (particularly those who haven"t played live before) won"t cross.
If the economy was booming and everybody was awash with cash then the demand might hold up, but as it is then moving it to £100 or above will change the nature of the tournaments.
And once you start looking at changes below £100 then it"s barely going to make a difference. Face it you"re never going to make a living from playing APAT tournaments, good players will get the occasional free good weekend, and the rest of us will just have to put up with the good weekends. That"s worked well so far, why risk it?