This shop is great for all party supplies. I usually go there to buy sets of helium-filled balloons for my kids' birthday parties.
The balloons are reasonable priced - standard balloons approx. $1 each and then approx. another $1 to fill with helium and arrange into a balloon arrangement. The special foil-like picture balloons are a lot more expensive - between $10-$20 per balloon, but that covers the cost of the balloon and the helium and the arrangement (if arranged with other balloons).
The staff are always friendly and polite and helpful.