I've just been through the same dilema, and it is very stressful. My partner is from a very large family, and I'm from a small family both of our families are all over GB.
We had the debate of where, it could have been several places, we looked at keeping it small, say no more than 25 people, so his family didn't go down the line of " you have invited one cousin but not me", we thought we could keep it small. Costs for this was about about £10k, inc honeymoon, but nothing too fancy.
We looked at something larger, say about 60 to the day and another 40 to the night and the costs were extortionate, once we added this up, this was near £25-30k.
One key thing, my other half hates being the centre of attention. He really wanted a very small wedding, if he had his was it would just be the two of us in Jeans at a Registry Office - I wanted something a bit more.
We have decided to get married in the Seychelles, we have booked the Raffles hote, where the wedding is free, and the hotel seems lovely. We are going for a week, and the cost is £5150 half board. With rings, dress, flowers, and phots (oh and something for him to wear), I think we will need to add about an extra £1,500, and them there will be spends, but we would need that for a honeymoon anyway. Organising it has been really stress free, the hard part was choosing which country followed by resort / location and then getting quotes. We have decided not to invite any one officially, but let them know when and where, so if they want to come, they are more than welcome.
The best bit for me, is that I don't have to worry about all of the stuff, you know, menus, seating plan, favours, presents for bridemaids / usshers, decoration of th venue, food tasting, cake, colour schemes, chair covers, bows for the chairs, table linens, cutlery etc etc - the list is endless.
All we now have to do is buy our outfits, send copies of the paperwork to the Agent, then make sure we get our flight.
Hope this helps.