Actually, it's a bit odd that Bulma DOESN'T have a suit of Saiyan armor. She knows how to make it (right after the training in the Hyperbaric Time chamber, she showed up at Kame's lookout with fresh suits of armor for the four warriors, and I doubt Vegeta's one person capsule came equipped with four changes of clothing (if any)so the armor is presumably Capsule corp manufacture) and given some of the dangerous things that happen around her, you'd thinks she'd want all the protection she could get. I guess the real reason is that, by the time she does know how to make the armor, she's largely retired from active, on site Z-fighter assistance.
