You could do it yourself, I used this technique to weld an aluminum part.
It was awhile ago,
but if I recall correctly, the main thing was to heat
the parts to be welded before
touching the alum welding rod to them.
And I bought the gas tank and rods at home depot, probably less than $30 total.
How to "Weld" Aluminum Without a Welder: 7 Steps (with Pictures)