In the interest of history... most Mini 9/Vostro A90 factory SSDs were 8 or 16 GB. 4, 32, and 64 GB were available, too. But they're more rare, since they were only available with Linux, and the big ones were very expensive.
Aftermarket SSDs are available in capacities of 8, 16, 32, 64 and 128GB. The largest models are very expensive, and therefore rare.
There never was the option for a standard hard drive from the factory. Maybe the 160GB drive option you're remembering was an external USB drive?
Anyways, I hope your new SSD
comes quickly, and works well.