Talking in generic terms.
"Don't buy any vise unless it has a rotary feature. like Juro says."
There are some cheap ones around. You can also buy used. Not much wear ever happens to any vise. Yes, some get careless and drop glue and epoxy over the base, but you will be able to find one that's in good condition.
Next, be sure it can holds the hooks you need. Some will hold a saltwater hook just fine, but try smaller ones? Small hooks will grab near the end of vise jaws, some vises often chip due to hardness problems. Look at the design. See if it is solid.
Lastly, you should have access in all directions to the materials being tied to the hook. Look for sufficient clearance to work on a fly.