The 84 Topps set is notorious for off centering and even staggered framing. You could open a brand new, untouched pack of 84 Topps and pull a Marino rookie that has never seen the light of day and it may only grade out as a PSA 6. A PSA 6 sold yesterday on EBAY for $35. For a point of comparison, you can buy an unopened 84 Topps pack on EBAY for about $50 with no assurance that it has not been tampered with or not dropped, etc. And you have about a 1 in 30 chance of it containing a Marino.... Elway is also in the set and comparable to the Marino card (a little less desirable/valuable) plus Dickerson and a few other lesser names like Duper, Craig, Long, etc.
In short, any raw (ungraded) Marino rookie out there is far likely to be a PSA 3 or 4 ($10-$15) than a 9, much less a 10. Oh, and it costs about $20 to get graded, if not more depending on the tier pricing which is an entirely other conversation.