Its the same round, the Europeans tend to call the .45 acp (automatic Colt Pistol) round .45 auto. Astra was a Spanish firearms company that stopped production around 1978 or so then merged with Star another Spanish firearms company and continue making guns under the Astra name for a few more years until Star went out of business several years ago. The later Astra pistols like the A80 are generally patterned after SIG pistols. I owned an Astra A70 .40 many years ago and it was a solid decent handgun but a little rough around the edges as far as fit and finish. As far a price for very good example, hard to say, some one may have a Blue Book of gun values handy and can give you some pricing. Parts will be hard to come by thats for sure. As far as quality of later Astra pistols, I would say only average at best. Blue Book may say its worth more but personally even for a 95% plus gun I would give no more than say $225-250 at best, since replacement parts will be very hard to find and its not a real collectors item. Unless you can get it real cheap I would pass and spend my hard earned gun money on something else, unless you have a special thing for Spanish guns like Astra, Star and llama. I do like some of the Star handguns and own a Star m43 Firestar which is a fine little all steel 9mm.
The word is a Swiss company has purchased the Astra trade marks and may start making guns under the Astra name again.