Welcome to vintage land. It's the best!
I'm also a big Jackie Robinson collector, and like you, I'm also obsessed with eye appeal. Unfortunately for us, that means we have to pay well above "comps" to get copies that we like, assuming by "eye-appeal" you mean centered cards without obvious flaws like creases, paper loss, markings, etc.
In my experience, I generally have to pay at least 1.5x "comps", and more like 2x, 3x, or sometimes even as high as 5x to get the cards I want. It just all depends on the card itself and how difficult that particular card is to find centered, and timing/luck. Sometimes you can find some good deals though, if you're patient (~1.5x comps). But you will almost never see a centered Jackie card that is free of major eye sores selling for average comps. The vintage market is ALL ABOUT eye appeal. You can have 3 copies of the same card in the same grade selling in the same auction go for $1,000, $2,000, and $3,000 entirely because of eye appeal. Vintage collectors are much quicker to give the middle finger to the number on a slab than modern collectors. That works in both directions. If a card looks over graded, like most do with old certs, then it will typically sell at a discount. If it looks under graded, be prepared to pay as if it were at least a full grade higher. That's pretty much how it works in these parts. If you're willing to buy nearly centered cards (~55/45) as opposed to dead centered 50/50 cards though, you can save quite a bit, as those do not sell for as much of a premium as truly centered copies sell for. But you'll still pay a premium for a 55/45 card, especially if it's 50/50 left/right and 55/45 top/bottom.
Definitely take the time to study the nuances of how vintage cards are graded. That knowledge is essential as a buyer, in my opinion.
Here are a few of my Jackie cards. Sorry, but these are not for sale
