What are experiences on finding collectors/dealers willing to "downgrade" cards?

[Smarti5051]

For those that have specific collecting goals and finite amounts of money to work with to meet those goals, what are your experiences "upgrading" your cards in your collection (or more specifically, what have experiences been looking for others willing to downgrade)?

To put the question is context, one of my goals is to get a PSA copy of 200 specific vintage HOFers. Some of the specific cards on my list are so far out of reach now, I have just called off the hunt until the kids get through college. For others though, it is a trade-off of quality vs time. I can get a VERY reasonably priced PSA 1 1934 Dizzy Dean Goudey. Right now, it is tempting to add one to my collection. But, as time passes and my collection expands, I will look back at the poor, tortured Dizzy card and think it would be nice to have a decent PSA 4ish version of the same card. Assuming cards continue to appreciate in the future, I could sell my PSA 1 Dean, pay taxes on the gain, and then start the hunt for a PSA 4 with some of the proceeds as seed money (the downside being the tax hit to have to liquidate the card). Or, I can try and find somebody on the boards or a show that has a better copy of the same card that is willing to accept a downgrade with the appropriate cash compensation to even out the value of the trade.

At base, my question is what others' experiences have been finding that willing partner to "trade down" when they wanted to "trade up" with cash (or additional cards). It seems like many of the trade posts I see (although less on this board) are folks with 100 shiny cards offering to "trade up" to a more expensive card. In my mind, I always think, "yeah, everybody wants to trade up." But, is that true? I have only been back in the hobby for about a year after a long hiatus (the last time I was this immersed in the hobby, hearing the word "ebay" meant you missed the beginning of the body of water the speaker was referring to). So, I am not really sure what the common practices are these days on trading.

In short, am I better served being super patient to save up for the exact quality I want on a card, or will I be able to scratch my immediate itch to build my collection without really hindering my flexibility to get the final collection that I want down the road?