The last time that I took this trip I stopped in Stafford and it was way cheaper (plus I had business there), looking at the day you are wanting (leaving just before 6pm, nothing later unfortunetly) I found this:

London Euston - Stafford (17:50 - 20:18) £23,50
Stafford - Manchester Picadilly (20:37 - 21:40) £7,20

It takes 3 hours 50 (almost double the time that the direct Virgin train takes). You can try other connection points, to look into the timetables and prices I find it quite easy to use The Train Line but they do charge you to buy the tickets so you should buy them elsewhere.