Depends on the price they are going for currently, how high your offer is, and how much you want for it. What is its condition?
If you provide a link I could probably help you out a bit more. I don't want to blindly advise you one way or the other without knowing the context, but it sounds like your mindset is in the right place about not getting too greedy. (Trust me, I've been there. I rejected a $300 offer for a Topps Chrome gold wave Hiura auto last summer, and only ended up getting $225 for it 3 months later.)
But again, context, context, context.
Edit: I was doing some research, and it really looks like this card is fluctuating quite a bit on the market right now, which makes sense given that we are threee games into the season and Robert's career and he just hit his first home run, so it may be a bit inflated right now. Assuming your card is NM or better, I would accept absolutely no less than $210 for it, if you really need the money like right now. But given the market over the past few days, it appears $225 to be pretty likely. I'd try to get $225 and be happy.
#COMMONCARDSMATTER
"The 0-2 pitch... SWING AND A MISS! Struck him out! The Philadelphia Phillies are 2008 World Champions of baseball!"
- RIP Harry Kalas