This DB9 (DR9) seems like a good compromise of price and quality. It has solid milled gold plated contacts, but the soldering leads are stamped metal crimps.
There’s a version with 100% milled pins, but it costs 5x as much and I’m not sure there’s much of a point.
Picked up a 0,5meter null modem cable for the fine price of $0.68 
Sourced three MAX3232 chips: Maxim/ADI original (5.9RMB), HG Semi (2.9RMB) & 3Peak (1.3RMB). You can see the huge price difference. I think the scalpers can get a pretty good price on the Maxim part, so it’s probably best to go with the original.
Capacitor Selection
The capacitor type used for C1–C4 is not critical for
proper operation; polarized or nonpolarized capacitors
can be used. The charge pump requires 0.1μF capaci-
tors for 3.3V operation. For other supply voltages, refer to
Table 2 for required capacitor values. Do not use values
lower than those listed in Table 2. Increasing the capaci-
tor values (e.g., by a factor of 2) reduces ripple on the
transmitter outputs and slightly reduces power consump-
tion. C2, C3, and C4 can be increased without changing
C1’s value. However, do not increase C1 without also
increasing the values of C2, C3, and C4, to maintain the
proper ratios (C1 to the other capacitors).
Maxim datasheet…
The capacitor type used for C1–C4 is not critical for proper operation; polarized or nonpolarized capacitors can be used.
The charge pump requires 0.1μF capacitors for 3.3V operation. Increasing the capacitor values (e.g., by a factor of 2)
reduces ripple on the transmitter outputs and slightly reduces power consumption. C2, C3, and C4 can be increased
without changing C1’s value. However, do not increase C1 without also increasing the values of C2, C3, C4, and
CBYPASS to maintain the proper ratios (C1 to the other capacitors)
3Peak datasheet 
Will definitely go for the 0.47uF caps.
Layout recommendation.
8-11 are UART1, 12-15 are UART2. I plan to bring out the CTS and RTS as well, so we’ll need two MAS3232 chips.
RTS is output to CTS input. Question: are these signals routed inside the serial cable, or do they need to be opposite on each device?