What accounts for Dutch Oven price variation?
I have owned many brands of cast iron and ceramic coated pans, here's the factors I've seen that effect the price:

Quality of materials: better quality coatings last longer and give better results
Refinement: some brands are more aesthetically pleasing, better designed, and have better finish than others. Some of these refinements may improve the cooking experience, some may just be looks
Name: This is a huge factor these days, some brands like Le Creuset have hiked up their prices enormously in the past decade to the point they are absolutely eye watering, yet their products haven't changed in design or quality

Of all these it's name that seems to have the biggest effect on price. I have some Le Creuset that I bought or got as gifts some time back, and I have since bought some department store branded ones (Linea, House of Frasier's own brand) which are 1/3 of the price. The department store ones look good, deliver good results and wear just as well as the Le Creuset ones. There are many brands to choose from, it's worth doing some research on what's available around you before you spend money.