I am a once a year (normally) skiier as well and decided to fork out on some skis finally.
I found the issue with hire skiis is that despite paying a fairly high amount they will not necessarily be that good. You can pay a little more to have the option to switched them, but thats more hastle to go through plus of course another set to get used to.
Last few years I have hired and my other half has used her skiis, I would say that whilst skiing is a bit like learning to ride a bike in that you can get back on and be up to speed fairly quickly its also like the bike in that if your used to a BMX moving to a racing bike feels different, even moving from one BMX to another is different...
So last year after the season I setout to buy a full set of equipment, i got some used once (claimed but seems fair) salomon boots, which are worth about £250 for £30, they have custom liners and are remouldabale more than once.
I got some Salomon Enduro skiis which new were about £600 for under £200, they were used (claimed) for about 3 weeks and have some scrapes etc on the tops but the bottoms looked good. I may get them serviced in resort this time.
If your willing to go second hand, and take your time to find the bargains you can pick up some great stuff. The boots were from a skiier who had purchased from too far up the range to suit their skiing ability, the skiis were from a guy who had 3 sets and had just bought another set so needed to make room.
My view is I bet I can sell either of those items for practically what I paid for it after this year if I am not happy with the performance of either/both item(s)
Carriage with Crystal is £35 for bothways so no biggie, similar amount with most carriers.
I would agree that boots are the first thing to buy yourself, after the first year skiing i bought boots then stopped for a while. On returning to skiing I just got into the habit of renting. The great thing owning your own is you can spend a few hours in them before you go getting yourself used to them again.
Ski insurance is a risky one if you rely on your normal ski insurance via your normal travel policy, I think mine was limited to about £175 for skiis last time (owned or rented) and most ski shops are likely to want more like £300 a pair if you lose/break one.
I think finding somewhere to store the skiis is a bigger issue for some than actually owning them!