If money is the issue and not time, you could always reboil the diluted canned wort before making the starter if you're concerned with possible contamination. There's definitely extra time involved with that though.
I know this isn't all that practical for most home brewers, but I've collected fresh yeast from a fermenter on brew day, and pitched it in the new batch. Fermentation has always taken off for me within an 8 hour period doing it this way. There is also more than enough yeast for a single batch, so you really don't have to be concerned with growing your yeast in the new batch via aeration. There's enough to kick off right away.
I've done this over 3 generations with great results. I can't seem to fit more than 3 consecutive batches in a row with my busy life, but you could technically do this for many many batches...like Picaroons, or the Pumphouse. Pumphouse pitches 20 generations before starting with fresh yeast again.
Anyway, this is a great way of ensuring your yeast is clean and healthy without canning, refridgerating, etc, and if you can do it over and over, you can take expensive liquid yeast and spread the cost over many batches.