I suggest checking FaceBook Market Place and eBay for used docks and hubs. Someone mentioned in another thread it was possible to find CalDigit TS3+ Thunderbolt 3 docks used under $100, so I went to FaceBook Marketplace and found one for $90 that took me a 40 minute drive to meet up with the seller at a public location. It lacks a MicroSD reader, but otherwise should make you happy.
At least know your options. A big question is whether you want 'just' a USB-C 10-Gbps dock or a Thunderbolt dock (or hub).
Some comments:
1.) For a Mac Mini accessory with its own power supply + SD and micro SD readers, I suspect you may find yourself looking at docks more so than hubs (bigger, more elaborate).
2.) While the Mac Mini 2 has a fairly elaborate of ports, when you upgrade to an M4 or later Mac Mini, it probably will not, so factor that in as you decide whether you want HDMI, DisplayPort, etc... Assuming you like to future proof and want this thing to be useful with your next Mac.
3.) While you may not currently plan to use a single Thunderbolt peripheral, a Thunderbolt dock gives you (hopefully) a 40 Gbps 'data pipeline' from Mac to dock, to supply transmission to and from all devices hooked to it. With a USB-C dock, that's likely 10 Gbps.
4.) You may find a new USB-C dock and a used Thunderbolt 3 dock fairly close in price.
5.) At least some dock USB-C ports often don't support video output, so don't assume just because there's a USB-C port on one that you can hook a USB-C display to it (USB DisplayPort Alt mode).
6.) Thunderbolt 3 docks, from what I understand, will only have one Thunderbolt 3 'downstream' port (so you could daisy chain another TB 3 device), whereas TB 4 and 5 docks can have more than one downstream TB port (double check on this, but I think I remember right).
7.) If you see a great price on a used item, read carefully...some are non-functional and intended to be used for parts, or it may be missing a power cord, etc...
8.) Plan to buy near a holiday and check DealNews.com and TechBargains.com (reputable deal sites I've used) and do a search for 'dock' or 'computer dock.' I'm a fan of Woot, too.
9.) When buying off eBay, I like to see a lot of ratings culminating in the upper 90's positive ratings from customers.