I am a 25B, information technology specialist. How likely am I to get my Army reserve unit to send me to a Sec+ class on orders??

Short answer is: You can very likely get the certification paid for, but it's unlikely you'll be paid to attend a bootcamp unless there is an immediate operational need (needs of the Army, that is) for you to have one.

Longer answer:
You may be able to get your unit to justify sending you to this course as part of an AT plan so you can at least get paid while you're attending. You can also just use you GI bill for these courses. Overall, it depends on how much you can sweet talk your chain of command and unit admin. Are they invested in you or can you demonstrate why you having this certificate will help the unit more than you attending battle assemblies? This website may have some useful informations, forms and regulations which you can use to help build your case:

https://atc.us.army.mil/iastar/regulations.php

https://www.cool.osd.mil/army/index.htm

Lastly, you really don't need a Sec+ bootcamp. Just spend 2 months reading the book and taking the test preps online and from the book. Then test. Bootcamps are a scam.

Some installations are offering them, check your nearest Ed Center. ASG Kuwait has an enduring Sec+ program for example.

That is a specialty course that isn't in the CA unit training tree for your MOS.
The shortest answer I can give you and the one with the best chance of success is for your commander to determine that he/she has an operational need for this capability and write up a ONS (Operational Needs Statement) next time the annual planning cycle gets briefed.
There are missions out there where this would be useful (Atlantic Resolve comes to mind), but whether your unit is one of them I can't say.

That would depend on the unit and existing funds if you are trying to go to a Sec+ bootcamp over 2-5 days. There should be an existing program for the Army to cover the cost of the cert though. I know the Marine Corps and Navy both do so I am just assuming but there should be a way to get the cert paid for. Be sure to download the Sec + app from Comptia. Use that and you will kill it.

Honestly just get a book and study for 6 months. i read a study guide and memorized keys words with definitions and took a bunch of practice exam and passed it on my second attempt. If you can get a contracting job there are some companies that will reimburse you.

I'm taking Security Plus right now. The text book is on skill port "CompTIA Security+ All-in-One Exam Guide, Fifth Edition (Exam SY0-501), 5th Edition". Test is $350 if your unit wont send you since it was kind of a drawn out process to get sent to Security Plus, because someone has to like you enough to help you with the paperwork.

If you're in CONUS now (and you have the time), check your local community college system Many of them offer curriculum and non-curriculum courses that are inexpensive and will prepare you for most of the vendor-neutral certifications. Although I was already SEC+ certified, I audited one of the classes offered locally and was quite impressed. I'm with the Eltee; save your money on boot camps. You'd do better buying the Exam-Cram books then taking the test when you're comfortable. I prefer a 2 for 1; getting a certificate of training from a local college campus (if possible) while gleaning semester hours toward a degree.

I personally think these IT MOS are bait and switch. We weren't given such assignments cos we were told there wasn't any immediate need for such duties. As i private I spent much of my time cleaning up, on KP, or guard duty because I was told these are more pressing matters. My skills were hardly called used in ARNG, so I reinvented myself with more useful duties that required math skills. Like map-reading, radio-positioning, and NBC weapons-NCO. These are fast promotional treks, and yes you can switch MOS in the reserves as your CO which are more likely to be promoted, unless you like peeling potatoes.

Considering that Sec+ is required to hold the most, or at least it used to be, the odds are pretty high. Get with your training NCO. Sec+ classes can be found in ATRRS. Since it is a required certification, the Army will pay for it upfront. There was a school at Ft McCoy for reservists.