Where is a good place to buy my bra size? Walmart

I need some help on finding the right place to get a bra that will fit me. I wear size 42DDD (depending on the brand, i might be able to fit in a DD), walmart used to have my size, and I was able to get them for a excellent price, but now they don’t! Where are some excellent places that carry my size for a excellent price (i don’t want to spend anymore than 35 bucks!)

I am going to a Halloween party next month dressed as a girl. I will be wearing a bra. But I have never worn a bra or know what size to buy. I am a guy with a 44 inch chest. Could anyone tell me what size bra would fit me. I have looked at bras at Walmart and they only go up to 40dd. Could I wear this bra size?

I just bought an XXL top from Ancient Navy. I wear a 36DDD in bras, and I was wondering if the XXL top would fit or if it would be too huge or too small. I tried on an XL at Walmart and it was way too small. I looked at the sizing chart and it said an XXL would fit a 46 chest, but I don’t have a tape measure Has anyone with my bra size had any luck with an XXL swimsuit top from Ancient Navy?