at Kids 4 Less or at your kids school
Nordstrom's (not Norstrom's) Online site carries many strapless dresses for purchase. The easiest way to find them is to use the search box and type in "strapless dress" or "strapless dresses".
You can find a strapless prom dress for cheap from the Salvation Army, Volunteers of America, Amazon.com, Good Will, and other secondhand and thrift stores. You can also find one a plato's closet.
You can get them at Delia's
One may find jumpers for a 3 year old boy at stores such as Babies "R" Us, Walmart and Target. One may also find these types of jumpers at Sears and The Bay.
Deb stores
Abercrombie Kids
There are many websites that have a wide variety of strapless dresses for sale. Nordstrom has strapless dresses online, and also many other websites that have multiple brands together in one place so you do not have to skip around.
you find out urself
There is a few places you can buy a strapless dress that is not to bling but not to girly. I would try looking at the Justice store and see what they have.
You can find jumpers (sweaters), from places like Amazon Canada, eBay, Petco, PetSmart, Walmart, Target. Nearly every place that sells dog food and dog collars will sell dog jumpers.
They are sold out on the Lipsy website so I doubt you will be able to find one. Sorry.
I would recommend a swim suit from the site alwaysforme dot com. A great suit id only forty dollars maximum, and you can go straps or strapless. Surf the Web