Well - you may want to wait until you hear from Father on this one before you buy anything special.
At one parish I used to belong to, adults presenting themselves for baptism would wear long hooded brown robes, they nearly look like monks! They step into the font, kneel down in the water, and have three pitchers of water poured over their heads. After they come out, they are given the same style robe but in white (and dry!), then they take their seat in the pews. So what they wear underneath is not important. They are not shown in street clothes at any time during the Mass. It really is very moving, and it is nice to see them all dressed identically - the sacrament seems to “stand out” more when you are not distracted by pretty dresses and new suits. But that’s just my opinion.
When I was baptized as an adult, I wore street clothes I didn’t mine getting VERY wet. I went into the font in the water up to my waist, then was poured over with water. Unfortunately this particular parish did not give us anything to put on before the baptism, and well, let’s just say I did not choose well in what I wore. My friend told me afterward that I came out nearly naked looking when the thin khaki trousers I had on stuck to me like a second skin and turned transparent!!! :eek: She destroyed the photos, thank goodness!! After the baptism I went back to the sacristy and changed into a white linen suit for the remainder of Mass.
So - anyway - I would check with Father before you buy anything new.