For Men, Women And Children

Apparently, Mario has now appeared in 200 video games, - that's some accomplishment for the little plumber who first appeared in the 8-bit game called Donkey Kong way back in 1981. The first official Mario game was Mario Bros., released a couple of years later in the summer of 1983. The most popular of all, though, was the Super Mario series which first appeared on the Nintendo Entertainment System (NES) in September 1985, and this was the first of a series of sideways-scrolling platforms game featuring the loveable plumber.
If you're looking to dress-up for a gaming event/convention or maybe an event with a retro 80s or 90s theme, then Mario is an excellent option. However, you could also dress-up as one of the other characters from the series of Nintendo games such as Luigi or a super mushroom. The best place to start looking is actually Amazon, because here you'll find a whole range of  well-known fancy dress suppliers (inc. Rubies, Henbrandt, etc.) selling their wares at very competitive prices.
Super Mario Fancy Dress Costume for Men
This is an authentic-looking costume which includes the boiler suit, hat and moustache and is available in small, medium and large sizes for adults. It also includes the "M" logo on the cap which some costumes don't have.

Despite being a lot cheaper to buy, this Super Workman costume featured above (by Henbrandt) has been receiving pretty positive reviews and is also available in green which is ideal for dressing-up as Mario's brother, Luigi. The outfit fits up to 46" chest and 36" waist, and includes the dungarees, top and hat, although the white gloves and moustache are not included so you'll need to buy them separately. Order before 12pm and the costume will be despatched the same day.

There are plenty of suppliers selling Mario costumes for women, but the most popular and highly-rated outfit is the one featured above which is being sold by Emma's Wardrobe at their Amazon store. It is available in sizes from 6 to 14 and includes the matching hat and gloves. The outfit is also available in green (Luigi) and with or without white stockings.
You may also be interested in these options...

This Deluxe Official Mario Costume is available direct from Nintendo's store on Amazon and actually is actually great value compared to other offerings. It even includes an inflatable tummy! 

However, these lower-priced outfits are also available and have good feedback..
Mario Moustache Fancy Dress Accessory

This moustache is the best-rated on Amazon and is perfect for the Mario look.

White Cotton Gloves for Mario Fancy Dress
I've also hand-picked these costumes and accessories with a Mario theme. 
Red Mario Logo T-shirt

More Costume Ideas