Google SCCA Sprite or Midget in Louisianna - mybe you can find a racer type with some spares - they're like pack rats and heroin addicts combined - they can't live without their racing fix, so they squirrel away spares like they aren't making them any more ( Come to think of it, they aren't)
Next thing is to look in the Yellow pages under used auto parts - Concentrate on the ads that say they carry foreign parts and start calling - All of these guys are in bed together and hooked up to a nationwide network of junk dealers, used to be teletype, now it's internet - somebody should be able to locate an axle for you.
Other than that, just don't panic - I'll bet your ten dollars to a bent hatpin that somebody on this forum will come up with an axle for you at a reasonable price.
Best of luck to you Randi...
Bob M.
P.S. the forum has many members in the UK - just look at their Avatars - maybe a judicious email to one of them would widen the pool of possibilities - Jolly Old England must be swamped to drowning in Spridget bits!