How did the buyer approach you?
At today's Bitcoin price, It's a decent starting offer, considering the below recent sales.
Would accept the offer personally. I'd place .al in the same category of obscureness as .lc and .im, if not more obscure. It's certainly not as well known as .ly, so don't let that blind you to the fact you probably won't see an offer come along that often.
bitcoin.lc - 338 USD
bitcoin.ws - 510 USD
bitcoin.ly - 5250 USD
bitcoin.im - 1510 USD
bitcoin.be - 1989 USD
Bitcoin had a hype in 2017 and only the first one (and first time I see .lc) is from 2017.
Such a domain on a highly (online) tradeable product has a certain value even in ccTLD due to country scope.
I admire what bitcoin.de has done for example, but also, launching a number of ATMs through a bitcoin.countrcode would be interesting.
I would consider 0.5 BTC, but not less. Thank you though...
bitcoin.co.uk 30,000 USD 2016-06-13 Flippa
bitcoin.ws 510 USD 2016-02-25 GoDaddy
bitcoin.ly 5,250 USD 2015-12-10 Flippa
bitcoin.com.au 35,182 USD 2014-12-10 NetFleet
bitcoin.com.au 23,000 USD 2014-04-16 Sedo
bitcoin.me 10,000 USD 2014-01-09 Sedo
bitcoin.im 1,510 USD 2013-03-06 Sedo
bitcoin.be 1,995 USD 2013-01-23 Sedo
bitcoin.be 1,989 USD 2013-01-11 Sedo
bitcoin.us 17,500 USD 2012-12-30 Afternic
bitcoin.de 21,420 USD 2011-06-29 Sedo
bitcoin.de 29,750 USD 2011-06-21 Sedo