Sales happen with the intersection of value to the seller and value to the buyer. Value to a buyer whose sole intention is to try and sell it for a profit is going to be lower than the value to a buyer who sees the domain as the home of their online business or otherwise playing a vital role in it. The reseller will only be making a one-time profit (albeit a profit they then reinvest into more domains, make more profit, etc.) vs. the end-user getting a recurring revenue source from the online business they've built on the domain, with the domain's quality potentially being a major contributor to how well that business does.
If you don't want to sell domains for reseller prices, don't sell to resellers, period. No reseller is ever in the business of paying low end-user prices to try and sell domains for higher end-user prices. That said, there's high reseller and low reseller as well...I myself do not sell ANYTHING under $50, and even $50 is a rare case, usually only with bulk deals or in very limited-time sales. Some people however are happy to sell domains for $10-$15 dollars, and many buyers only buy domains for that or less. Great for all them, but I have my pricing limits and I sell plenty at the prices I seek which includes end-users who buy names at my retail prices, so it works for me.
As a buyer, I look for the best deals for me. If it's a domain that I intend to use, while I may look for a good deal, I will even consider paying end-user prices for domains I feel are excellent for what I need. I do that because it's WORTH IT...if I'm going to develop a serious business, I feel I SHOULD get the best I can get and care more about quality than getting a good deal, and I think that's what most end-users are thinking...or at least the ones savvy enough to be looking to buy on the secondary market v.s register whatever's available. Resellers on the other hand need the good deal because more than likely, their intent is to provide a good enough deal to another buyer of it that will get them a good enough profit for the flip to be worth it. So price levels are different because the focus of the buyer is different.
The main issue for all of us is that unlike the end-user market, the reseller market is easier to reach and sell to...we're all here, DNF, Sedo, etc. Hopefully sometime in the future, the end-user market will be that way too, but as it is you have to hunt down potential end-user buyers and hope they'll buy and/or list-n-wait.