One stereo or two (stereo and mono) cartridges?

Why spend so much? There are many excellent cartridges available for way less! No need for a mono cartridge. A stereo cartridge plus a phono stage/preamp with a mono switch is fine. Unless you are a 1% high roller spending $10K is a foolish idea! A Hana Umami will sound excellent! There is one for sale now here on Agon for $2.7K with low hours. Grab it!

I've always played mono records with stereo cartridges.  I understand there is less noise with a mono cartridge, which could be useful.  However, for me, I put the money into a better stereo cartridge and tonearm.

Rather than split the cost, why not adjust the percentage on the number of mono records you have versus the number of stereo.   If you have 30% mono why not spend $7000 on a stereo cartridge and $3000 on a mono?   That will help you budget you stereo dollar but how the cartridge sounds is probably more important than just a dollar figure.

Note that all new recordings will most likely be stereo, too.  Also note that many mono recordings are not RIAA compensated, so spending a lot of money for a mono cartridge could be somewhat of a waste. 

One great stereo cartridge would be my choice. Actually recently heard a My Sonic Labs Gold Signature (I believe retails at 9k) that I'm saving for. Incredible musicality and tone with a soundstage to die for.

@luis223344  Having both a stereo and a mono cart is great fun. In general mono carts are a little less costly so I would say 60/40 or 65/35 stereo/mono for budget.

Will you have two tonearms? Or use a removable head shell tonearm and swap carts as needed? 

Solypsa

Planning for two arms. Good point about the relative cost of carts. thanks!