Often we work with retailers with very tight budgets for marketing. This is really common and even if you don't have a budget at all, this doesn't necessarily mean you won't be able to get any marketing done. There are many things you can do for free, and lots of things that only cost a little bit of money, and plenty of ways you can do things that do cost money without spending any of your own!
Most independent retailers are acting as resellers for manufacturers, and depending on your relationship with these manufacturers (and even if this relationship is via a distributor) you should be able to call upon their support for marketing. You are, after all, selling their products!
Make friends with the marketing departments of your suppliers and call upon them to support your events, with mentions on their social media channels, email newsletters or any other outreach they have to consumers. Make sure you're listed as a stockist on the websites of all brands in your store, and schedule regular meetings or telephone calls to keep a constant flow of support from them. Depending on the nature of your business it isn't unrealistic to ask them for samples for testing, repeat product training and even staff to represent the brand at any special event days you plan.
If you're considering including a high-profile ad campaign as part of your marketing plan, perhaps in a local newspaper or even an exciting outdoor media opportunity that can't fail to bring you new customers, but have concerns about managing the costs of such a campaign, it might be worth your time to build a proposal that shares the cost with your suppliers. If you're looking at a campaign of 6 different points, over a run of 6 months, you could work with a different supplier each month and feature their product heavily within each ad, on the basis of splitting the cost with each separate supplier. Your suppliers will be keen to see your marketing plans and if you are reasonable with your requests and perhaps even connect this with ongoing commitment to take in a new product, it will be hard for them to say no.
Having worked for brands trading with independent retailers, we've seen the marketing departments repeatedly working with the same 10 or 20 retailers, despite having hundreds of retailers selling the product. This isn't favouritism or for any other reason than those select retailers were keenest to work together on campaigns and were vocal about what they wanted.