Why Buy a Speech?
Does it really make sense to spend money on a custom speech?
The answer to that question really depends on circumstance. In most situations, I would actually like to discourage people from spending money on social speeches, because it seems like just one more way we spend money unnecessarily.
People at a birthday party or wedding don't really expect the world of a speaker, and they're usually on the speaker's side. I believe a social speaker just needs to open his or her heart -- especially because there's no set length of time they need to speak. Just a few kind words can do it. If s/he wants a little help (especially with wedding speeches), there are plenty of resources that can provide openings, quotes, closings, etc., to enhance the personal stories and fill out the speech.
On the other hand, even people in social situations sometimes have a lot of money and no time to even look for or through these online resources. In this case, having a speech writer lend a hand can be worthwhile for them.
When it comes to professional speeches though -- whether for a business speech or any kind of motivational speaking -- I think it makes extraordinary sense to buy a speech from a professional speech writer unless you're a professional writer yourself.
In this kind of situation, money rides on the speech, and you can't afford to disappoint the audience, no matter what you're getting across. Honestly, I used to write speeches for every kind of social situation, but I've focused on business speech writing because I think this is the only area (in speech writing) that consistently makes sense for people to invest in.
Because business or motivational speeches are usually longer than social speeches -- in some cases much longer -- they involve a lot more research, require many more ideas and organization, plenty more revisions, etc. And of course things have to be said in a way people resonate with and in words that people will remember. All of this calls on the skills of a quality speech writer.
So if you're wondering about whether to buy a speech, I do recommend it any time money is on the line. In a social situation, go with your personal situation. If you've got the time to think out a social speech on your own, by all means do. The audience is likely to appreciate just about anything you have to say.