!887 is by far and away the most common date for Victorian Half Crowns. I bought my example in good EF with full luster and mild patina (has fewer dings than coin pictured) for £7 (AUD $15) a coin show about 15 years ago.
Lots of them were hoarded by the British Public for the Jubilee Year.
I thought I got a reasonable bargain at the time, but I keep seeing high EF to choice Unc examples turning up for sale reasonably often. They always seem to be available, if you go looking for them.
Grading wise, if there is the tiniest amount of wear on Victoria' ear, they should grade in the EF to good EF range.
For Unc grades, look for undisturbed luster on the high points - both sides.
For quality of strike, I look at the front faces of the triple lions in the shield.