(*****I am not saying Saskia does not love animals and I am not being snipey, its just that the opinion from that perspective and your situation is like comparing apples to cabbage, no relevance, sorry Saskia not trying to pick on you******)
Yeah am not taking it personally or anything. Perhaps I should explain my position a little more, I think I came of a little harsher than I meant to. Tis long winded - skip over it if you like.
I love and respect all animals a lot. I am vegan and have never intentionally eaten an animal, nor have I ever intentionally hurt one. My oldest cat is 14 and we (he lives with mum currently) will keep him forever. I have spent thousands of dollars on our dog for surgery (my mum spent her money on cosmetic surgery - still not over that, your teenage unemployed student daughter should not have to fork out for that) to keep her alive for a while longer. I love animals.
To me though horses are not just animals you keep around. For one they cost A LOT more. You can feed a cat for $10 a week, but in my experience for a horse you are looking at $100+ a week. To me horse riding is a hobby, and something that I wanted to compete in. My first horse I got when I was 11 and was a little galloway who was sweet and all, and he taught me how to fall of, and then how to not fall off, and how to do all these things which was fine. After a year or so though I was getting tall for him, and I wanted to do showjumping, something that he had no aptitude for (my shoulder lives to tell the tale). Sure I could have kept him forever, and had a horse that was too small for me, and been constantly frustrated when he didn't perform how I wanted him to, and he could be constantly uncomfortable being pressured into doing what he didn't want to do. Instead I sold him to a lovely girl with a farm who was looking for a second horse to do mounted games and pony club which he was perfect for. As far as they know, about 8 years on, they still have him, the mother uses him for a trail horse or something.
My next horse was a schoolmaster showjumper who taught me all about that, and I then purchased a rising two year old to train myself. Then my parents told me that I couldn't keep two horses as it was costing too much, so I sold the schoolmaster (wasn't that upset - he wasn't a people horse).
Couple of years on and my baby was a 5 year old and for reasons I needed to leave home, and my mother said she would not continue paying, and a 17 year old out on her own finds it difficult to afford a horse, so I sold her. I miss her, and I still visit her, and I keep in touch with her owner who adores her, and does little dressage comps, and endurance rides (never thought a 17hh clydie cross would be good at that) and I think she is in a better situation than I could have given her, given my financial situation. She is the only horse I ever regret selling, and its not that actual selling her, looking back I know it had to be done, its that I will never have her again.
Its hard selling horses, and everyone I sold I cried for, and missed, and regretted it for weeks after but I think if I would have kept my first horse then I would have had to choose between the horse as a pet or horse riding as a hobby. I don't know if people here can fork out $100 a week for a pet, I can't.
Again, as I said I would sell a purely competition horse at around 13 - 14, in my situation if I wanted to keep competing I would need the money from the first horse to finance the next - much over 14 and they really drop in value. To OP, if you horse is healthy you can probably get another 6 years of competition out of her, maybe more, and more riding after that. Her age will probably in no way affect her transportation, nor will it hinder her in other aspects.
Still $12,000 to send her over. That is a lot of money to me. I get like $180NZD (around $130US) a week (for rent, food, everything), and I have never lived in a house owned by my family, my mother was a single mother always renting. To me that is a lot of money.I just couldn't justify spending it on that. But I guess if you have the money then do it.
This may be contrary to what I said before but I am a firm believer in no regrets. If you think you are truly going to regret it forever if you don't bring her over, then bring her. Regrets haunt you forever. Even if it turns out bad its better than it eating at your for eternity. Money comes and money goes, its just paper. Although be aware whenever I come into money it goes, so my philosophy may not be the greatest. But I don't have regrets, not ones that will eat at me at least.