I purchased my 3.5 qt Le Creuset french oven at a Le Creuset outlet on sale for just under $100. The salesperson told me that the outlet sells "seconds" that have superficial exterior blemishes that don't affect the cookware performance, and they sell discontinued colors. The one I purchased was a discontinued blue made for Williams-Sonoma. (My DH picked the color, and it had the added benefit of having the lowest price.)
I just googled Le Creuset 3.5qt, and it looks like everyone's prices are competitive. So sales and coupons may be your best bet. If you don't mind "seconds", outlets and discount stores might save you more if you buy it on sale or clearance.
Just to give you an idea of pricing: the 3.5qt retails for $255, but major retailers are listing it for under $200. Sur La Table had the 3.5qt on sale for $130 during their annual cookware sale a couple months ago, but only for the new color made for Sur La Table (fennel). I saw the 3.5qt at Marshall's Homegoods for around $150 (I think). (And of course, I bought mine on sale at a Le Creuset outlet for under $100)
(Just an FYI, I decided on the 3.5qt, because any bigger was a too heavy for what I wanted in an everyday pot.)
Good luck & HTH!