Oh...my condolences....
Well, a 900 gb SSD averages around 300-500 bucks, whereas a PS2 with all the trimmings is around 100-200 bucks regardless of model (trimmings = cords + controller(s) + memory card(s)). Games are a null issue due to purpose, but your still gonna need a storage device for the OPL ISOs. Any USB stick will do ya, but a PS2 is very picky about what HDD you plug into it, and you still need a specific Mirco B cord that splits into 2 USBs (one for transfer, one for power). You'll also want a 128Mb Memory Card to hold all the game data, but those are like 20 bucks so it's not even an issue.
So, at most a PS2 set up should be around 300 bucks, and there's not telling how expensive an SSD could be. However, the SSD can hold more thant just PS2 games, and would conceivably be more useful.
The bottom line, go for broke on the PS2, but only after you fail to find a better deal on an SSD. It would be better to replace you SSD in long run, but it just might not be feasable at this time.