Instead of buying her the regulator you could always go with a gift certificate or one of those VISA gift cards for the amount you're willing to contribute then she could add some cash to the pot and get the reg SHE wants.
Get a cold water reg it doesn't have to be the most expensive one on the market, it can even be used. I purchased my first reg out of a rental fleet, a MK10 and I think both second stages are 250's. I'd be willing to sell it but it needs to be serviced and might need a new pressure gauge, I replaced it a couple years ago with a matched set of Dive Rite G2500ICE's because I got a great deal on them.
This is true to an extent and depends on where you buy your reg. The shops around here generally sell the warm water regs for less than the cold water ones.
Let me tell you a little story my LDS owner told me. Someone comes in to buy a regulator, wants the cheapest one they can get. LDS owner asks where they will be diving and the answer is locally. Tells customer the "cheapest" reg isn't suitable for all of the local diving because it's a warm water reg and recommends a more expensive but still "cheap" cold water reg. Customer says he can't afford it and insists on the warm water reg. LDS owner tells him NOT to take it deeper than 60 feet at the local sites because it WILL free flow in those temperatures. Customer promises he doesn't intend to dive deeper than 60 feet around here. Later date customer makes 100 foot dive with regulator, free flows, fails to deal with it correctly and dies, one of his two buddies on that dive dies trying to help him.
Purchasing the wrong regulator for the local environment was the first step in that accident scenario. Dive accidents are a series of mistakes, not single event catastrophies.
Ber :lilbunny: