If a "songwriter" wants to buy your songs - I think you may be getting a bad deal. I could understand if a singer/producer wanted to buy songs - but if songwriters want to buy songs it means they don't have confidence in their own material - so they want to take credit for your talent. However, if you think these songwriters have "connections" or business options that you don't, maybe you can use them to your advantage.
Perhaps you could "sell" part of your song. By this I mean he gives you $300 and you make him a co-writer (25% or 50%). If you truly believe this songwriter can get your songs heard and even sell some copies of recordings - it may be worth giving up part of your "copywrite". And if this person really believes in your material he should be happy to be part of it. Obviously the best thing to do is "sell" the use of your songs, while maintaining the copywrite.
I've sold a few songs (for very little money). I'm pretty sure the people who bought them didn't get rich (I know I never hear them on the radio). But I made certain business decisions that cash in hand was better than nothing. And I have several songs with copyrights that will never make me a dime.
Now I'm also getting royalty checks for a song I "produced and co-wrote" (I added a bridge). The actual songwriter took a "risk" by giving up part of his copyright and I took a risk by accepting a percent (of possibly nothing) rather than getting cash up front for my time and expertise (oh yeah, and the use of all my recording gear). He then "sold the song to a publishing house, who get 50%, another risk. When all is said and done - the song was recorded, is selling copies and the original writer is getting 1/4 of the royalties, his "partner" is getting 1/8 and I'm getting 1/8, (and the publisher is getting 1/2). But, that 1/8 is better than nothing (in particular when the checks comes "every few months").
I know a playwrite who sold the rights for a play to a Hollywood director (yes a legitimate young director being pursued by various studios). The director wanted to develop a screen adaptation of the play. The deal was stuctured so that at the end of three years the rights reverted back to the playwrite. So the playwrite made money (selling the rights) with a chance to make more money (if the movie did well) and protected the rights to the original work (if the movie wasn't made). A reasonable business risk all the way around. (There's still a year left on the option, so, we'll see what happens).
I'm sure I'll get slammed for my opinion, but I have seen so many songwriters copywrite thier material and many "start their own publishing company". Fine, your song is protected and published - but if it sits in a "catalog" where no one hears it what has been achieved? Sometimes, it is better to sell a song than to have it trapped in your head, but only if you believe the person buying the song can really do something with it - or - if they offer significant amounts of money. Does it make sense to sell your material - sometimes, maybe.