I prefer buying small lots or single items for resale, which is why I rarely have over 1,000 items for sale.
This little "ugly duckling" arrived today. It's Trinidad SG18 (1d) Slate-blue, and it looks the worse for wear.
In fact it's VFU with four clear margins, as SG comments "(October 1858). Impression less distinct, and rarely showing more than traces of background lines".
This is as good as this issue looks, although I'll give it a bath to clear 168 years of dirt and grime.
Catalogue value is £850. I paid £75 including postage from an auction site in Sweden