I'll toss my hat in,
I say because of the racing/motorcycle nature of the beast, you want a proficient welder to do the work. You don't want to mess with the heating and time welding the repair as oxidation will make the aluminum junk structurally. Not the right place to hone your new-to-me welder and new-period skills.
Go to the nearest Miller/Lincoln/Airgas type store and hit up the guy behind the counter as to whom to take the work to. That guy knows most every decent welder in the area from sales, and can likely point out the fabricator who buys the most aluminum TIG rod...
Other option is to hit up what ever local Trade school or Tech collage is around. See if the instructor will do it as a demo to get the new recruits interested in practical applications for their potential new skills :-)
Side note: I've never struck an arc with anything nicer than a Miller Synchrowave LX, the best, period. That being said, for my home shop a top offering from Everlast was WAY more cost effective and left me with cash for the TON of accessories, water cooler, gas bottles, consumables, grinders, clamps, $350 helmet, gloves, vest, sleeves, test plates, better torch(es), blah, blah, blah. I can swing the lower duty cycle of the lesser machine and I can have one for AC-DC TIG/Stick, one for MIG, and a Plasma cutter to boot. The reality is most of the time they sit idle despite my fondest ambitions. Sweet to have when the need arises though.
"Never underestimate the trechery of older men." Tom Lipton