Influencers normally get given product plus payment to collaborate and promote brands. If you only have contra available and not monetary compensation, then make sure you're making it worth their while and offering a fair exchange.
Obviously, the higher the contra value you offer, the more influencers and better quality influencers you will receive. To give you an idea, if you are offering a product/service to the value of around $75-100, you would be expecting to receive 1 in feed post from people with around 2k-5k followers. If you are offering a product/service to the value of $500, you would expect to receive 1 in feed instagram post from people around 20-30k followers. Most people with over this number of followers require payment for their services.
A good sense check is ‘Would I do this collaboration myself? If someone gifted me this product/service, would I want to post about it?” – if the answer is no, rethink your offer