wolfie1a
Based on your needs, you could look into
SEL 500 series (587 (Diff & O/C) & 501 (OC - dual) - Low Cost -minimal, but proven platform, or
SEL 300 (387 (Diff+O/C +++) - modern platform (higher priced) & SEL 351 (19" relays) Fixed (but available expanded I/O) or
SEL 700 (787 (Diff & OC) + 751A (O/C++) lower cost, more comm options, expandable I/O. Programmable Push buttions
I tend to think for the size and application you are seeking, the SEL 700 series is a good choice, as the I/O can be expanded, the communications options (past and future) are available and it fits into a panel cut out roughly the size of old GE & Westinghouse 50/51 relays.
The SEL 500 series are a bit older technology and have limited I/O.
SEL 700 uses the green "Phoenix" removable connectors (some like, others dont). SEL 300 / 500 series can accept a standard #12 AWG ring type lug.
SEL has on their website "Retail" Prices, and on line configuring (which updates the pricing).
Please don't forget test switches, whatever you do!!