If your money thing was indeed true, you can just go and tell him. I'm a guy, and I like women who make themselves clear - it saves us a whole lot of trouble.
"Uh, ya know, I cancelled cause I was outta cash, and I didn't wanna make ya pay." would sound nice. Maybe a bit broke (of course!) but it's a good start. So you can just add something like "But if you want, we can do something that doesn't require spending at all. I wanted to see <insert something you could buy LATER ON, or just same lame excuse here please>, you wanna go with me?".
If you're still afraid, ask yourself: why NOT do it? Heck, if things go wrong, just remember to be fair with him. He'll get it, if he's no dork. I bet he'd prefer to go out and (maybe) don't work out later on, than just not trying at all.
And missed chances don't come back, keep that in mind.