Catalogs are generally sent in spring and early summer. Terms vary widely. Will they replace or refund in case of problems. Compare Prices - Prices are not the same. Our opinion is that you do get what you pay for.
Cheap bulbs are generally cheap for a reason.
Smaller bulbs generally give smaller and fewer flowers. We can't control it and we certainly don't encourage such practices. Ask other gardeners on the WEB about their experiences with specific suppliers. DaffNet members will be happy to offer their personal opinions. You can easily find out which varieties do well in your part of the world.