Upgrade: Speakers or Amp. mod?

I have an Onix SP3 which I love. I recently decided to have it modified with better caps etc.
However, a pair of speakers have recently been put on sale at Audiogon which are the next model up from the version I currently own and also really like.
Which upgrade would you make? Should I have the amp modified or should I upgrade the speakers?
I cannot afford to do both now.
I await your replies.
Get the speakers, like Rsfphil said. The speakers are on sale now. The mod will probably be about a constant price.
Just to play Satan's attorney, there is one reason to consider the amp: speakers often sound better when the downstream components feeding into them improve.

However, it sounds like the speakers in question are sort of a rare find. So then you can look forward to *really* having phenomenal sound when you're able to afford the amp in teh future.

So ultimately I agree with the other posters, but wanted to at least mildly advocate for the other alternative.
I'd mod the SP3, if you can,t hear an improvement than I'd upgrade the speakers. How can you know what your current speakers are capable of if you don't give them a test? They might match perfectly with the modded unit.
I found that with my last pair of speakers, every time I upgraded something upstream, they showed me more of what they could do. It was only when they were truly the weakest link in the chain that I finally upgraded the speakers.
If you buy the speakers, are you going to sell your current pair? If so, maybe you will be able have the mod as well.