Well it depends... here are some things to consider:
Will it save you $19 worth of time if you buy it? (US minimum wage is $7.25/hr, so little less than three hours worth by that criteria)
Will it fit into the style of your game, particularly the other slot machine things?
Do you have the right software to process it? (I assume GIMP would work, though)
Could you find something similar cheaper?
I would say that price sounds steep to me, but you might have a hard time finding free images without running into licensing problems (assuming this is a for-profit game), so it might be worth it to save the hassle. I would google around a little bit first, though.