I'd like to be able to get my hands on gear more locally, so here's my tuppenceworth.
If you don't want to get too specialised with Rob Allen gear etc, and aim for a wider market then, generally speaking, Omer is a good, popular (and, some would say, better quality) alternative to Cressi. They have a good quality range of guns, suits, and fins (and their fins tend to have a wider foot pocket, which means that people who cannot fit into the narrower Cressi fins will be able to fit into the Omer fins (and they have a wider range of fins than Cressi too, with different stiffness to suit different people/conditions, compared to Cressi). So Omer is probably one of the the main, and better, alternatives to Cressi (and one of the most well known).
Dive Hunters, such as the Sevylor Dive Hunter SDB120, are very popular with a lot of people. As is the Princeton Tec LED Shockwave dive torch (you need to be very specific about that though); Suunto D4 dive watch (has a free dive mode on it, which is considered very useful by many, but is expensive, so if you can source a cheaper freediving watch then happy days). Many people are buying dive cameras, such as the Go Pro series - and there is much debate at the moment about which is the best route to go down with these. Neoprene under vests (and even shorts) are very handy at this time of the year and early season. It's not alway easy to source nice hydrodynamic winders either, for your float line.
Apart from that, I have trouble getting my hands on decent consumables at short notice, such as neoprene socks of varying thicknesses up to 7mm (Seac do well fitting warm ones, but they always wear through on the soles very quickly, which isn't very jolly at this time of year) as well as decent warm gloves suitable for spearfishing at this time of year (Mares do a 5mm Tri-Glove, with 3mm on the palms for dexterity, and wrist seals, which are great for spearfishing - I find the cressi gloves fall to peices very quickly).
I find drop weights very useful (attached to your float line, they clip/tuck into your belt, and can be 'dropped' to anchor your float to the bottom whilst you do something else). I seem to be losing a lot of Stringers/fish keeps lately as well.
Hope that gives some extra ideas,
If I think of anything else I'll let you know.
Gaz