Worth spending another $250 for an SSD?

In the process of building a new PC. So far I have it down to these parts from Pccasegear making the total just over $1000 (including delivery of $130). Antec P280 Black Super Mid Tower $149 Intel Core i5 2500K $235 G.Skill Sniper F3-12800CL9D-8GBSR2 8GB (2x4GB) $59 ASRock Z68 Extreme3 Gen3 Motherboard... show more In the process of building a new PC. So far I have it down to these parts from Pccasegear making the total just over $1000 (including delivery of $130).

Antec P280 Black Super Mid Tower $149
Intel Core i5 2500K $235
G.Skill Sniper F3-12800CL9D-8GBSR2 8GB (2x4GB) $59
ASRock Z68 Extreme3 Gen3 Motherboard $139
Samsung SH-222AB SATA DVDRW Drive $22
TP-Link TL-WN951N Wireless N PCI Adapter $3
ASUS Radeon HD 6850 DirectCU V2 $169
Antec Neo Eco 520C 520W Power Supply $69
Standard ATX Power Cable $2.50

I'm considering getting a Crucial M4 120GB SSD for another $249?
I don't really have money to blow, though I can't decide whether it's worth forking it out currently or waiting till I have more money a little way down the road.
Suggestions?

Also feel free to change the build if you like, I'm all ears open to other parts (preferably cheaper) possibilities.
Thanks.
Update: Thanks for your quick answers guys! I'm interested in what brand of PSU and specific model you'd choos for this build. As for videos of SSD, I've seen a lot similar, plus they're still very prone to fail or have issues at some point from all the reading I've been doing on them. Still thinking... show more Thanks for your quick answers guys!

I'm interested in what brand of PSU and specific model you'd choos for this build.
As for videos of SSD, I've seen a lot similar, plus they're still very prone to fail or have issues at some point from all the reading I've been doing on them. Still thinking about it though....
Update 2: @rowlfe Thanks for you detailed answer. 1. As for wireless, my current desktop is using it, but only through a mediocore netgear usb dongle and I'm having problems with it cutting in and out as it chooses to do so. However with the wireless card in a pc, from all the reading I've done I've come to the... show more @rowlfe Thanks for you detailed answer.
1. As for wireless, my current desktop is using it, but only through a mediocore netgear usb dongle and I'm having problems with it cutting in and out as it chooses to do so. However with the wireless card in a pc, from all the reading I've done I've come to the conclusion that the dropouts are much, much less frequent as it is attached to you mobo card which picks it up as though it were an ethernet cable. I know wireless is degrading to the connection in every way imaginable. I personally would be running cable through the whole house but the landlord won't allow it, even though I'd not charge him and have everything flush with wall adapters and what not. Therefore I'm adding wireless adapters and what not that run on a different bandwith to neighbours, just trying to solve it without having to take this douche to court.
2. As for the ssd, the points you've brought up are exactly what's putting me off of getting
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