What do you say when people know what you paid for your flip? Feeling defeated!

[Summer Segeleon]

Ugh. Just showed my first property today and was caught a little off guard by the fact that the guy had checked public record and knew what I paid. I'm selling a 2bed 2bath mobile home on 2.66 acres for $25,000. He was asking how much money i had into it, etc. etc. KILLING ME> I told him" Look. I checked other similar properties with less land and they are listed for $50K.  He offered me $15K for it (bc he can see that I paid $10,250). I just said " I have that into it" .. But ANYWAY, what do you tell people? How do you justify the high markup when you've negotiated a good deal? How do you get around this?