Professor Roy Schotland of Georgetown did some sleuthing (actually, he simply examined some forms filed with the FEC) and came up with the following statistics on donations to Swift Boat Veterans:

Swift Boat Veterans for Truth Contributions
Contributors giving <$1,000 0 Contributors giving $1,000-$4,999 473 Contributors giving $5,000-$9,999 23 Contributors giving $10,000-$24,999 4 Contributors giving $25,000-$49,999 3 Contributors giving $50,000-$99,999 0 Contributors giving $100,000-$199,999 1 Contributors giving $200,000 or more 3 Total Contributors 507 Total Contributions $1,907,785.00 Source: FEC Form 9, Swift Boat Veterans for Truth Contributions, 9/10/2004

It is fascinating that most contributions were relatively modest ones (i.e., under $5,000). $5,000 is something of a magic number, because that would be the maximum limit if Swift Boats, a 527, were to be considered a political committee under the FECA (again, putting aside the constitutionality of that limit).