Well, the problem with that is, if you offer at the values that are advertised noone is buying them (at least not mine) so you are kind of stuck. Without selling you won't have enough money to buy what you want, but you can't go significantly under the price if you don't want massive losses.
Is your item something popular that people would want, or is it something not commonly used? Is the item you want something popular and in demand? Not all heirlooms are equal, even if they take the same amount of effort to acquire. So if you have something that's not so popular, you may have to accept that it won't sell for as much as the item you want. For example, I see a +1 light lance is listed for 250k while a +1 heavy lance is listed for 350k. In my opinion, the heavy lance is still a much better value. Even if the light lance were only 50k, I'd still only buy the heavy for 300k more.
Perhaps try setting the price to an amount that is lower than most other items at that heirloom level. So for example, if you are selling a sword, there may be a buyer who is interested in either gloves, body armor, or a weapon, and is looking to buy whichever of those is cheapest. And be realistic about how much you think people want your item, rather than believing there is a minimum price per heirloom level regardless of the usefulness of the item. I mean, nobody wants heirloomed stones except as a novelty item.
BTW, I've traded a +1 steppe horse for a +1 heavy lance. I just made a bunch of listings for all the items I'd be willing to accept for the steppe horse, plus a gold-only offer that was a decent amount less than any other horse.
I don't sell my heirlooms because I have no reason to, since I use them all on a daily basis. No one has offered me any money for my heirlooms, either (but this point is moot, since they're not for sale anyway).
The point I was trying to make was that you are not selling any heirlooms because you value them more than the amount of gold you could get for them. However, you would be willing to pay the current market prices for the heirlooms you want to buy, if you had the money, even though you say those prices are screwing people. So in reality, the fact that you're willing to buy but not sell at those prices indicates that those prices aren't too high.
I actually think there is a bit of a shortage on the market for armors with a decent upkeep cost. This is especially true for gloves. I bet someone could sell some heirloomed gloves for more gold than they would need to buy most of the weapons listed.