I would go for a red, dry or semi-dry. A Cabernet-Sauvignon, Merlot or
Pinot Noir. The wine will be stored in a cellar (not a wine cellar),
where there is little to no light at all and no heaters. I guess the
temperature will fall below 15C in winter, but it would be interesting
to measure the temperature...

I will also store the bottle horizontally. I have no wine racks at the
moment, but it I get a a few good wines I'm willing to invest a rack or
two.

Price... difficult to say... I was thinking of buying between 5 and 10
bottles.

Without considering the price but the other conditions, what good wines
fall in this category?

Thanks
Max