It sounds like a really petty thing to be thinking about but I've been looking for a large bun ring for ages. When it comes to hair I tend to go with "bigger is better" and I think the normal size bun rings are a bit small for creating a really glam bun look. The only large bun rings I could ever see were on Ebay and/or really expensive - plus it's tricky to see if they actually are much bigger.
So I was excited to see that ASOS - probably my favourite retailer - were selling a large hair donut. I ummed and aahed about buying it as it's brown (my hair is pretty light blonde) and it promptly sold out. It's back in stock now so I snapped it up, at £6 (-10% student discount card, I'm going to be so sad when I finish uni and have to pay full price for things!) and the fact that I could return it if it looked ridiculous, I decided I wouldn't be losing out on much.
It's definitely bigger than a normal bun ring as the picture above shows and it actually isn't that dark brown so I can just about get away with it, with a lot of rearranging my hair to make sure it's covered. I absolutely love it though, it gives me the right size and look of bun that I want. I'd say that if you have thin or short hair (especially if you're blonde) then this might not be for you as you may not have enough hair to cover it up, I've only got just enough hair and mine's quite thick. I need a spare pair of hands (or at least eyes) to make sure it looks neat and concealed.
A way to get round this, and I'm not sure how successful this would be, is to buy a cheap weft of blonde hair and somehow attach, wrap and secure it around the bun ring so it doesn't matter as much if a little bit of bun ring is showing through. Like this (normal/small) one that I bought from Ebay ages ago that came with hair already on it (I'm coming across as a bit obsessive now aren't I!):
So if you love big buns like I do (oo-er, I mean as in hair!), then I'd recommend checking out the ASOS Large Hair Donut, available for £6 from ASOS.