Define the target for your group and what pain point you are solving for them. You can work on a lead sharing concept and can charge for that. Also, you may want to start a sponsor slot where external business can present their offering in this group.

In ideal scenarios, there is no reason to increase the price based on the revenue unless working involves increased efforts to a substantial extent. I would quantify the efforts required in hours and get a quote from the freelance consulting accountant. Based on your details, it appears that you do most of the bookkeeping activities and so the consultant has to validate and do Govt formalities. Unless you are doing some specialized business where you will need to defend or work with Govt officials for certain things within accounts, you should be paying charges wrt to the effort involved and yearly inflation rise.

Your question doesn't give full clarity of Product or any challenges you have about going to big companies. If you have the budget, things could be much easier as you will have an agency to help in this. In the case of cost constraints, you will need to find innovative ways to reach companies which could be existing connect, cross-selling, usage of the forum, thought leadership ..many ways. Feel free to reach out if you have any questions.

If hiring salesperson can help to close the deals, then I would find ways to do this. Before this, you want to check answers to below questions. 1) Are you able to close the deals without any support? 2) If 1 is Yes, are you having sufficient bandwidth to close the current pipeline? 3) If 1 in No, then you find the salesperson who can help you. 4) You want to do the calculation on sales pipeline and see the overall business opportunity and likely money you need to spend. You can always do scenarios like optimistic & Practical. 5) You might get somebody do this part-time as well if you find the ways. 6) If you don't require face to face meeting, the task could be much easier. Feel free to reach out if you have any more questions.