My `77 came with a boot cover, albeit one without most of the hardware. Back in `88 when I got my car no replacements were available - or at least none were available at a price I would consider paying. Nor was I then (remember: this was pre-web, pre-Ebay) able to find any replacement hardware.
I got around this problem in a way that may make shudders run down the spine of originalists: I created my own mounting system using strips if beige velcro on the side chrome strips (Beige blended well with the car's color) and made my own rear metal attachment loops out of aluminum bar stock and heavy wire. With the top down (and my Spider's top is almost always down!) the velcro could not be seen and the rear connector went unnoticed.
For twenty-two years that makeshift boot cover did its job but slowly it started to look a bit shabby, the vinyl drying out, cracking and shrinking. Last summer I had to drive with no boot cover on at all. Unacceptable! But what to do? Now, unlike, when I got my car, boot covers are available. Some not too expensive but shoddy. Others like the ones sold by International Auto Parts (AIP) beautifully made -- truly equivalent to the original but oh, the prices! With hardware $365! And even without hardware $235.
But last winter AIP had a one day sale where almost everything - and this included the boot covers - was 25% off. I bit the bullet an ordered one, sans hardware. I also ordered the hook set so between that and my handmade rear loops she'd mount properly without the need for the velcro. AIP being AIP the cover (along with several other major restoration items) were delivered within days. They waited, unopened in thew shipping boxes, until this past week when I finally took my Spider out of Winter storage.
The boot cover was at first glance everything I could hope for. Heavy vinyl, beautifully pleated and stitched, and with two heavily padded sections just like the original. But what's this? No snaps? No hook straps? These I found were packaged separately without even mounting instructions. And there was no cut opening for the rear loop hardware. What the *$%#?
I called IAP. The rep told me how much he hated it when their parts vendors made unannounced changes to a product as was apparently had been done here. What could be done? He suggested I sew the straps on. And the snaps? No suggestion was offered. I then emailed IAP and explained the situation and asked how I should proceed? The response was that they recommended me having the straps and snaps installed by an upholstery shop. This answer was NOT acceptable. So I called IAP with a request: Would they allow me to return this non-hardware version and send me one with all the hardware and do so at the 25% off price that had been available for one day last Winter?
I expected to have to speak to a manager to arrange this. My leverage was to be my twenty plus years as a costumer. But none of that was necessary. Jake, their excellent sales rep (I'd dealt with him before), simply worked out the details to allow me to return the originally ordered cover (way past the normal return period), at IAP's expense (they are sending a pre-paid shipping label), and a new cover with all the hardware was being sent out right away (it has already been shipped) at the full discount with no shipping charge.
So finally, after 22 years with a make do my Spider will have the beautiful boot cover she deserves. And that'll go with her new IAP top (being installed this coming week at AVA in Dublin NH). Woohoo! And just in time for Spring (if/when it ever truly arrives).
-don
Also there was no cut out for the "fish clips" (the rear metal connector) so I'd still have to cut the vinyl to put them on and that'd leave a cut, unfinished, unturned and unsightly opening. Oh, and the snaps weren't on either! 
Some people name this cover a "parade boot", because it isn't intended to be used at highway speeds. I share your feelings described in an earlier post about this cover completing the look of the Spider. Even though my new canvas top is perfect, with a restored frame and a few extras, the car looks better with the boot cover.