"1730" must be Pilar Aranda, NOT Garvey (they use a "1780" label, sorry).
Therefore you need not feel taken in at all, as I don't know what $ they fetch. $100 is about as much as I remember seeing for a superb PX (and apparently that's what you got anyway, why care about the date??) but I ignore to what extent the absurdly diminutive production of these wines (often 150 bottles per year) may have provoked a boost in prices.
Of course, you know what your enthusiasm was about and you're free to feel disappointed, but in general I'd say there's no such a thing as the product you dreamed about. Vintage sherry is very rare, and the old dates in labels usually refer to the date when the solera was initiated. The fact that it is refreshed evry now and then makes it impossible to be certain about exact age of blends, but the best often average 40-60 years.
My favorite PX for my money average 30 and I can't imagine any better.
Having said that, PX from Montilla-Moriles (not exactly sherry region, but not an inch behind) sometimes carry a vintage date (1975 latest release, for 14$), and the museum releases of Bodegas Toro Albalá include wines from as early as 1939 (for a hefty couple of hundred, and no one is quite sure they're any better that younger stuff).
You see, Sherry is not Madeira in the sense that AGE (on an "older is better" basis) need not be so desirable after a certain limit. I have many old olorosos of about 20-40 years of age that are somewhat aggressive/spirity in the mouth (due to extended aging in wood, and evaporation). The nose is glorious but I don't enjoy drinking them as much. With a PX the problem is certainly not that, but a vintage PX from 1730 (if it existed) ought to cost several thousand bucks and be only 10 times as interesting as a 30-50 year old solera version, just for the sake of age, an auction rarity. Meanwhile you should be able to enjoy the best solera versions from (Spanish prices) 20-70 . IMHO you ought to be happy, at least about prospective repetitions/incursions in this field.