I also have had many young plants from "One Pound...", and have bene very happy with them.
If you wanted just 10 species.......oh this is difficult...!!
I would choose a plant from each of the main groups (as per Hunt), because then you would have a good representation, so:
1. Mammillaria longimamma or Mammillaria surculosa - subgenus Dolicothele
2. Mammillaria sheldonii or Mammillaria grahamii - for the Ancistracanthae
3. Mammillaria haudeana or Mammillaria longiflora - for the Longiflorae
4 & 5. Mammillaria bombycina and Mammillaria bocasana - for the Stylothelae
6. Mammillaria carmenae for the Lasiacanthae
7. Mammillaria decipiens camptotricha for the Decipientes
8. Mammillaria rhodantha for the Heterochlorae
9. Mammillaria spinosissima for the Polyacanthae
10. Mammillaria haageana for the Supertextae
11. Mammillaria geminispina for the Leucocephalae
12 & 13. Mammillaria heyderi and Mammillaria magnimamma for the Mammillaria
14. Mammillaria karwinskiana or Mammillaria mystax for the Polyedrae
Sorry, I didn't stop at 10!! There are more........and once you get bitten by the bug, hundreds!
Obviously this is my personal choice. Other people might have other favourites. It would be interesting to know.
All of these should be OK if you can keep a minimum temperature of 5C. That is my winter minimum and they grow fine if dry by early October and start watering in March - for the UK at least.