I think computers are great to have for vacation diving and quite frankly are much more practical for this sort of diving than any table. And I've got nothing against gadgets, or saving to afford something you want, but I don't see how dropping close to a grand on a computer makes any sense in your situation. Plus if you're renting your other gear maybe it makes more sense to put that money towards getting your own? That will likely do way more to increase your enjoyment of diving.
There are a couple downsides to your idea of buying one inexpensive computer now and a second very different computer later. For one, its considered bad practice for 2 people to share a computer. Now if you are sticking close and doing every dive together, and diving only on your own, maybe that works for now. But if you do any boat dives, realize the op may insist the person without a computer stick to table profiles, which means their buddy will have to as well, making the computer somewhat useless for that. There's also much to be said for you and your husband having the same or similar computers, and at least the same algorithm. Personally in your situation I'd buy 2 inexpensive Nitrox capable wrist mount computers (and sort out the prescription mask situation.) Then start spending your money on other gear. If you really discover you want the expensive toy in a few years and have excess cash to blow on it, have at it.
Another thing about computers, they fail occasionally. To some people that does not matter, but if you get into the this more, and find yourself on an expensive trip far away about to lose precious dives because your computer crapped out, having a backup computer is priceless. 2 inexpensive computers will be of much more use than one expensive one, especially if the one croaks. There will always be people that say use tables as backup, but practically speaking that simply doesn't work when you have been doing multiple multi-level dives for many days.