Before you purchase the Elvis jumpsuit, keep in mind that an Elvis jumpsuit which the ‘King’ himself wore will cost you more, as compared to a one-off jumpsuit for Halloween. Decide your budget and consider your options accordingly.
Visit a costume rental shop in your area and see if you can find a reasonable replica of Elvis’ Vegas jumpsuit. If you find one, rent it for as long as the shop's contract terms allow, or for the duration for which you will need the jumpsuit.
Nudie was Elvis' tailor during his later Vegas years. If you plan to get an Elvis jumpsuit for long-term use, consider getting professional advice from a tailor familiar with Nudie’s work. It would be wise to commission a tailor comfortable with tailoring jumpsuits, and embellishing clothes with studs, rhinestones and embroidery. Only a tailor who has mastered the aforementioned skills will be able to create the bejewelled look which was a prominent feature of Elvis’s dressing during his years in Las Vegas.
Elvis had a fuller figure during his Vegas years. If you want to impersonate that look, you will need to get a bodysuit as well.
Consider talking to rock memorabilia collection curators to determine if any of Elvis' jumpsuits are on the market. This will help you establish the authenticity of the jumpsuit if you wish to buy an original.
A number of celebrity memorabilia auctions are held every year. Seek out such an auction in your city. It would be a good idea to preview the merchandise put up for auction by looking at an advance copy of the auction catalogue. This will help you ensure that you are going to the right auction, and bidding for the right thing.
If you buy an original, get the jumpsuit mounted in a perfect display case. This can be done best by a professional textile conservator, so consider hiring one.