Yes, DVDs are just irresistible.
Am building on my HD collections but whenever there's a great DVD sale, am always tempted to haul it in. With the proliferation of upscaling DVD players and really awesome panels, you can come closer to HD quality so collecting DVDs is still a worthwhile investment.
The question is, with the HD disc discounts in Amazon which places it relatively cheaper vs. some DVDs, will you rather get the HD title? Special DVDs (e.g. Limited Edition, special packs / cases, OOPs etc) are definitely eye candy but one has to check his priority - super PQ/AQ, never mind the extras & novelty factor OR you're an authentic collector of rare and exclusive DVD releases with special packaging and tons of bonus materials / extras? HD-DVD was balancing things out with the 'extra' content (interactive at that), but BD has yet to really focus on this criteria.
Personally when I started collecting HD discs, I told myself I'll just liquidate my DVD coll and divert it to HD titles but as time progressed, I found it possible for these two formats co-exist in my racks. Bought new Oppo and Samsung scalers to match up the PQ - yes HD is still amazing but with the right scaler and panel, one could be a happy camper.
HD is my new passion but DVDs are just an integral part of my A/V life (for now at least...)