I would definitely bite at the chance to pull $50k so I think you're right - that valuation would be too high.

I could walk away for $10k. That puts the company valuation at $40k. Before we brought on the last 2 owners, we talked about creating a separate agreement between me and the original founder where he pays me $9k back over time if the company makes money. So I think the $40k valuation is a good place to start.