Chances are you've already got show kit but having just had to buy a new stock I realised how wide the equishopping range of competition wear is.
Thinking along credit crunch lines check out this jacket with 30% off. For eventing, dressage and showjumping black and blue jackets are fine. Tweed jackets are also fine although if you're hunting tweed is the norm. The only exception is that at intermediate eventing and above you need a black or navy jacket.
The tails problem! It's actually only compulsory to wear top hat and tails at ** or above eventing. That said, most people tend to wear them at * as well. Despite BE discouraging this practice - whatever people tell you about not having to chances are you'll fit in more wearing one... Top tip for top hats. Unless you're willing to shell out for a custom made Patey chances are your top hat won't fit perfectly. Fear not! All you need to do is get a bit of foam tape used for fitting hats around the head band and it'll fit like glue. Sorted.
Helmet wise, eventers tend to wear 'skull' helmets with a coloured silk XC and swap to a black silk for the SJ. Although quite a few have separate helmets specifically for showjumping which can of course be worn for the dressage as well- yes please!
As well as that if you're eventing at novice or above you can wear a 'beagler' for your dressage test. It's worth noting that these aren't actually protective but some say they look more elegant....
Wow, that's just the hats and jackets! The choice is yours and mostly comes down to preference....
Before we move on though, check out Equishopping's range of hat covers and silks - there's some pretty funky ones!
Breeches wise it's cream, white or beige for nearly everything. My only thing here would be getting white breeches clean - horses have that annoying habit of slobbering down the only clean clothes you have...
Finally we're down to the boots. Seniors (above 17) are actually supposed to wear full length boots. However, given the price if you couldn't run to a pair then boots and gaiters can look pretty good - will people really notice?... The advantages of a proper pair of long riding boots are fairly big though, they give a lot more support to the leg and will really help you get a more secure leg position which can only make you safer... worth thinking about.
Doh! I've missed two things out. Underwear and shirts/tops. White or cream is the usual for shirts. I'm pretty sure there's no rules governing what pants you can wear so go for it. Although, specific underwear for riding is more comfy!