You can get a pattern for a wine bottle vest which you can make yourself online. There are many options available online for free, or alternatively, you can purchase a pattern on websites such as Etsy.com.
I found this cute waiter wine vest on Etsy, and the price of £3 seemed really reasonable. The benefit of shopping online for a pattern is that you can view a greater selection, let's face it - these are speciality items - so it's unlikely that a crafts shop on the high street would stock much variety.
In many cases you can simply download the pattern so you can get started right away. Here's the link to the pattern pictured, in case it's the one for you - Waiter Wine Zest.
Websites that sell wine cover patterns
If you prefer to get your hands on a professionally-made wine vest first, you could stall try your local craft shops and stalls. But don't be afraid to ask the staff for more information - if they don't sell them, they may be able to direct a retailer who does!