I was drooling over aluminium trailers and they make lot of sense if you tow them year around, but for limited use they are cost-prohibitive, not saying that in case of any troubles - finding good aluminium welder is not going be easy.
Like with anything in life, you can compare initial price, cost to operate and resale value.
But the cheaper trailer I bought did the job and even last time I pulled it was 2 years ago - I keep it as garden shed/wind breaker, having emergency car hauler just in case.
Heck the $3000 I paid is less than Home Depot bigger sheds and I can redo my landscaping in couple of minutes whenever needed.