How much will you really save by purchasing the rice and sugar in 50 lb bags? For instance, I can often just about match per pound my purchase price of 50 lb bags of sugar or rice with what I can buy at a discount grocery store like ALDI. Their product is just in a 4 or 5 lb bag
For what it is worth, I buy my 50 lb bags of sugar by the pallet, each one weighing over a ton, and usually several at a time with other pallets of items to save on the trucking. There is a slight savings there, perhaps a dollar or two over the 50 lbs but the convenience is more important then the small savings to me.
If you are going to repackage it, does it really matter how it comes? The 50 lb bags rip so easy anyways, and mice will get in it if it is not repacked. From the pallet load perspective, the 50 lb bags sugar tends to flatten out and hang over the sides of the pallet, which with those thin bags is just asking for damage when moving the skid with a forklift.