In Theros (2013) they really seemed determined to find a balanced one
If you're building your first Commander deck, add in 8 - 10 depending on your Commander cost
Being able to break out a thoroughly annoying black deck, though
Per our Grixis Death Shadow example, for Cardhoarder you would set your card value limit to about $415, and for Manatraders you would choose either their Premium plan ($350 card value limit) or their Gold plan ($750 card value limit)
She will be astonished that you crafted her something, demand that you teach her how to do it, and get so turned on by your resulting demonstration of crafting prowess that you will not get to finish the lesson, if you know what I mean
The second a store gets them in stock, resellers are there to scoop them up