The OP's figures appear to be from the old Grenadier 25mm range. These are closer to true 25mm and, the humans anyway, appear small against modern 28mm ranges.
The figures Alien Dave has identified as being from RAFM are actually 15mm - originally released by both Citadel Miniatures in the UK and RAFM in the US. RAFM still produces these figures (Citadel got eaten by Games Workshop), and they're still as good as a lot of current 15mm figures.
I have a few figures from this alien set (and have recently painted up the Virushi for use with my 15mm figures) but have no idea as to the current value. There are people who collect these figures so you might want to consider posting on either the G+ or Facebook Traveller groups if you'd like to shift them.