Honestly, They kind of found me. I post up pictures and other goofy things on my business Twitter, and customer reviews using DnD related hastags. They get shared, and the owners reached out to me. I have been very lucky in that regards.
To search out podcasts/youtubes to partner with, and keep it budget friendly, I would google search "DnD Product Reviews" And reach out to a few people about doing a product review. Check out their previous videos or posts to make sure they fit with your company. It will cost you a bag and shipping but it is certainly cheaper than spending $200 or up to sponsor an episode. I also would start with only one review a month, so you can track which ones work out better for you, and listen to them so you can make the changes to improve on the product. Because no finished product is perfect, especially in the beginning.
If Facebook and Instagram bring you the traffic, certainly put your focus on those. Join loads of business oriented and hobby groups. Convention groups are also a great group to be in. Got to be super active in those groups, take part in give aways they have (again that is going to cost product and shipping, but still pretty cheap in terms of advertising costs and can be written off as such for taxes) Just got to be sure to set a budget for yourself on participating in those. Fans love buying items for their favorite youtubers and podcast crews, so the more active you are in communities the more chances you have a fan sharing your product with them. XD Word of mouth is god for small businesses.
For me personally, I have not really focused on Instagram. I have a business page there but have been building up my Facebook and Twitter first. Maybe another member in the group can share their experience in advertising on Instagram.
