Launched last month, the 30-day effort was meant to raise £15,000 online for Yes community groups by next Saturday.
Supporters were asked to donate £3 or more online to "give our local groups materials to distribute, venues in which to hold meetings, pop-up stalls to take to public events, and potentially even a local Yes Scotland presence in their community".
However, by last night the move had raised less than £6000.
Yes Scotland last revealed its income in April, when it declared donations of £1.7 million. This included £1m from EuroMillions lottery winners Chris and Colin Weir, and £342,000 from the SNP.
This weekend's disclosures by Better Together will put pressure on Yes Scotland to follow suit in the coming days.