how expensive is love?

gosh i love a good "animal friends" picture.

"You may as well give her your bass boat, hunting equipment, fry daddy and put your wallet on top and give it to her, because that's what it could cost you. If it doesn't cost you, it isn't love."
Last night, my beautiful bride and I were listening to a talk on marriage and the rustic, proverbially wise speaker shared the previous statement. Note: This was not in reference to a divorce settlement but rather in reference to what it takes to love another well.

The statement was absolute: if love is to be given, there will be a cost. I know that love is a choice, whether we're aware of it or not, to give preference to another person.

But this statement provoked a new facet, a new definition to my understanding of love. Does love always have to cost someone? Does it require time or money, emotion or strength, or simply effort to do that? 

I'm not an economist but I can remember from my college days the concept of "Marginal Benefit", something that will drive someone to give a resource.
Marginal Benefit is defined as:
The maximum amount a consumer is willing to pay to consume the additional unit of a good or service. In a normal situation, the marginal benefit will decrease as consumption increases.

This tells me that human nature is to continue to pay, to consume, as long as it's beneficial. Applying this principal to human relationships, why would someone love, chose to sacrifice on a consistent basis for another person?  How is that always beneficial for the lover (lovee)? And what's the limit on this? I suppose consumption, paying, loving would stop when the benefit is exhausted.  I know human intentions are impossible to interpret but I know that their is a perceived benefit in everything we do.

I don't know if I've really made a conclusion here, but I know that I claim to love many people and I don't know what it's costing me. What does it cost you to love others? I can see a correlation in my life between the people I've made effort for, and have made effort for me and the significance of those relationships or lack thereof.
The question I'm thinking on is "who do I want to love?" Who am I willing to absorb the cost for to communicate to them that I love them? I hope this doesn't exhaust you and I, but I think I say I love people but I haven't been absorbing a cost to do so.
I know that one of the most beautiful spiritual principles I've ever seen is that God's kindness draws me to repentance (Romans 2:4). That Him absorbing the cost initially to communicate love to me, to communicate His feelings towards me is the most motivating truth I'm aware of. I find motivation to love God and others from this, regardless of what I currently perceive about their feelings towards me.
What motivates you to love others?