If it low budget, you should to hard work to build a SEO and marketing to expose your forum, using low amount to let people advertise to your site will be good movement to collecting funds, do not make image of your forum bad let scam site advertise on your site, its should be selected. Also like what i have said above, uniqueness features probably the most influential to attract people join.
Let's take an example https://cryptocointalk.com/ that site still pretty crowded, they have good altcoin giveaway, which be a plus point.
Thank you, I will be very pleased if you join. Together we can spread the new bitcoin forum.
And I will keep your words in my mind, thanks for your suggestion.