Check out the D&D board games. Each comes with 30-50 minis and costs $40-50.
There are also a variety of things like this:
https://www.amazon.com/dp/B00W5WSN5A/ref=cm_sw_r_cp_apa_iBKwAbE208QG2
SCS Direct Monster Mini Action Figure Playset- 100 Horror Toy Miniatures w 13 Unique Sculpts - Dracula, Frankenstein, Giant Spiders and More- XL 1/32nd Scale Character Accessories https://www.amazon.com/dp/B00W5WSN5A/ref=cm_sw_r_other_apa_i_1Z79EbWVD1X7P