Medicaptain,
I can't agree more than with what the others here have said.
My partner has finally been dragged kicking and screaming below the waves, and is starting to build up her kit. There are items that I would ike to replace of mine, and we thought about trying to get a good deal buying two of a kind.
Firstly, we realised immediately, with the exception of the regulator, and possibly computer, nothing that is suitable for me is suitable for her.
Secondly, If you are spending enough money with them they will give you a good price anyway.
If you are going for equipment similarity, then I would suggest
1 - same reg setup
2 - have same BCD inflator regardless of BCD make chosen - shops will do this for you - most come with a basic inflator, and can be upgraded. The club I was in had a mix of Scubapro and Buddy (a british company) jackets. so that the regs were interchangeable, we had scubapro inflation valves fitted to the buddy jacket, at no extra cost.
3 - when you get a computer get them the same algorithm - there are several manufacturers that use the same maths, but they all present it in different ways. you need to play with computers first, and decide what features you want. certainly my computer is different from she who must be obeyed.
4 - get everything else to your personal choice.
This has the advantage that the MAJOR bits of kit are interchangeable, but that you also have you own, that will be comfortable for you.
As a lot of the equipment is personal choice, I would suggest that as everyone else here has said, get some diving in first. Dive with different styles of kit, find out what type of diving you are doing, and what kit is most appropriate.
This is one of the reasons that PADI has pretty much taken over from BSAC in the UK providing entry level qualifications. On PADI courses you almost always get provided ALL the kit. If you don't buy a Mask / Fins / snorkel it is provided, BSAC as a club based system used to make you buy mask fins snorkel, suit, and in some cases BCD and Reg as well before you could do the checkout dives. PADI stores have found generally that it is better to provide all the kit, and then encourage people to spend money when they start diving, building up good store-client relationships. This also goes to a lot of the PADI shops actually running clubs, where they make very little money if any on regular trips to training sites etc. but they make it back on future courses etc. and equipement sales as people get more involved (and obviously the store organised trips to nice places).
Personal opinion is that your kit should evolve, rather than suddenly all arrive at once. This is partly to avoid costly mistakes. $1800 for kit before you have started the lesons is a lot, unless of course you are a milionaire!
Q - How do you make a small fortune diving?
A - start with a large one.
Don't fall into this trap!
Jon T