Invitation Etiquette?

Hi,

I mentioned in a previous thread that I`m one-half of a planning committee for a surprise 25th anniversary party. The party is in early summer (June), but we`re starting to compile a guest list. Because our budget is tight, we`re trying to limit our number of invitees. Our family falls into one of two categories: those who live in the immediate area, and those who don`t but would be able to make the trip in a day or weekend.

Our guest list right now tops out at 95 people. Naturally, we`ll have some no-shows, but with our luck we`ll get 90 yesses when we`re only hoping for about 50! Is there some sort of etiquette for these sorts of invitations? What I mean is, if we don`t invite the relatives who live more than 6 hours away, would that be considered rude? Also, it is necessary to invite guests out of common courtesy, even if you don`t think they`re going to come because they rarely if ever show up at any of your other family functions, and you`re never invited to theirs? Our family has fractured over the years, and I`d hate to be the cause of additional hostility all because we want to throw a nice party on a shoestring budget. Any advice or pointers are very very very much appreciated! Thanks!