Hey Alan!
There are some other Ghost hosting providers that might be fitting for your case, as Cathy mentioned. Disclaimer, I run one of them (Magic Pages), but always try to be as unbiased as possible here in this forum.
If you have around 10,000 subscribers Midnight or Magic Pages might be the ones that could work for you. The others (recently summarised them here) might be a bit too limiting in terms of the emails they include.
Midnight has a plan for $21 per month that includes 12,000 emails every month. That could be a good number of emails for your newsletter, since the number of members/subscribers isn’t limited: Pricing - Managed Ghost blog hosting - getMidnight.com
At Magic Pages I am currently re-working the pricing structure. With the new monthly prices, you could get 10,000 emails for $12/month ($5 for additional 10,000 emails). Same as Midnight, there is no limit on the number of subscribers: Monthly and Yearly Plans In Addition To Lifetime Offer
Gloat (@dan is running that) is offering 20,000 emails/month for $19/month, again with no limit on the number of subscribers: https://gloathost.com/