I checked for DTW July 23rd for 7 days with Budget:

(I always like to have a base rate for comparison.) Then I checked with the Budget car rental discounts that you have.

Each Budget car rental discount code gave the same rate; approximately a 10% discount. That is quite common, especially during peak season (like summer). Basically, the rental car company will only discount so much in the summer, because demand is higher than supply.

I noticed a special on the website for 50% off weekly rates at airport locations, and a special for compact cars for $199 a week.... but both of these specials required a pickup by June 30th.

As you continue to use discount codes, you will get a feel for which ones, if any, give you better rates than others. I would say to always check using at least 2 codes, but you may want to check all budget discount code rates, to be sure. Also, those membership programs that you mentioned, my have rental car discount codes with other companies as well. You can check that out on our Car Rental Discount Codes Page.