Price and shipping
500g (about 160 ml) will set you back about $144 from Sigma Aldrich in the US. If you can't pick it up in person then you can get it sent to an educational establishment in the US, then your main problem is shipping. It can't be sent by any of the normal carriers and must be sent through a trucking company and then it has to be Hazmat approved, pricey.
After you've got it, as others have mentioned, it is seriously nasty stuff. Bromine burns are probably second only to HF burns in terms of long term problems, and personally I'd stay clear of it. I do remember my school having liquid bromine in the stock room back in the 70s, but then we also had all of the available alkali metals and mercury as well, most of which are now banned from school premises.