You could try things out with a Platinum Preppy for about 5 USD. Past that, a Pilot Metropolitan, or a Lamy Safari would be good entry level pens, in the 20 USD range. For 100-200 USD, you can get a very nice pen like the Pilot Custom Heritage 912, or a Pelikan M200. I'd recommend trying out the cheaper options first so you get an idea of what sorts of nibs you like.
"Additionally we had been running with far too much delay in vacuuming which meant lower load on the system, but more idle time in maintenance."
So, vacuum wasn't given the resources to keep up with their load, and it's not clear if they were supplementing with manual vacuums during quiet times. Nor was it clear when they started reacting, as PostgreSQL (also outlined in their documentation link), will start squawking about wraparound well before it shuts down, or the monitoring they had in place for whether or not autovacuum/vacuum was keeping up with the workload, or the number of locks their application was taking (locks can block autovacuum).
Adjusting the autovacuum settings by table will give you finer control over the postgresql.conf parameters to better match the workload for specific tables, as well.
Partitioning would have also helped make the actively written part of the table smaller, and older data could be vacuumed with VACUUM FREEZE, or deleted later. There are extensions to help make that easier.
Regarding monitoring, check_postgres.pl would give them an idea that their vacuuming settings needed adjustment sooner, or their application locking needed to be adjusted to not block autovacuum.
https://en.wikipedia.org/wiki/Audrey_Tang