Weapon mods from missions

So they are new to me, ive been doing missions and i have just over 300 mission credits, theres a grip that increases accuracy an for whatever reason it says special offer so im assuming its on sale, is it worth picking up or am i better off waiting for something else? Does special offer imply a sale or is it something else??

Special offer is a discount ...  Mods appears on mission shop time to time but special offers on them are rare ( at least for noob like me)

So far i bought standart grip, Standart Breaker, Reflex sight, Holographic Sight, and extra magazine and none with a special offer...

Here is list of Mods and their effects incase if anyone wonders ...  https://www.torn.com/wiki/Mods_Inventory

^^ same as he said, and, just another info, u can't get a tier 2 mod without buying the tier 1, so u see that standard grip and u say (oh i'll just wait for the tier to special offer to pop) that won't happen, so u gotta buy the tier 1 to get the tier 2 unlocked, tho i would suggest u save the credits till u have like 2.5k-3k before u start buying them, incase some book just pops there and u really want it, if you're not interested in books then feel free to buy any mods u like xD 

I'd have to reaffirm Pachico's point about holding off until you have over 2.5k mission credits, because certain books are very valuable such as Ignorance is Bliss. What it does, is while activated allows you to keep happy over your happy cap and train a month at 99,999 happy. Why that matters is because early on that can lead to many months worth of training done in a single month.  In fact, for players even at the 3 million stat total range that are Xanax free, it can still be worth many months of training. It get's somewhat muted as you have more and more battle stats, because its most significant impact is when your stats are really low, though even waiting till 50 million stats would give you the most stats for it it is strongly argued to use that book as soon as you can afford a decent training regime.

Weapons mods guide:

https://www.torn.com/forums.php#/p=threads&f=61&t=15979865&b=0&a=0

Keep in mind you can't add every mod to your gun.  You can only add two mods to a weapon at a time.  If you own more, you can change them out, but at any given time, you can only have two attached.

So you don't want to buy every mod that turns up.  Most of them aren't going to get used due to that limit, so pick out which two you really want to use, and just wait for those to show up.  Save your mission credits until they do.  The higher tier upgrades cost a lot of mission points, and you don't want to spend all your mission credits on stuff you will rarely or never use and end up missing out when a high tier one shows up on the mod you like the best.

I've been using sights and lasers, which is a popular combination.  Sights and lights is another popular combination.  If you want to look through the whole list (undulation linked the guide above), you can make your own choice, but if you want the simple solution, pick one of those two combinations and only upgrade those.

Mission credits should only be spent on mods that you expect to use, or on books.  (And not all books are worth buying.)  Anything that shows up which you can buy with cash, you should buy with cash not mission credits.

The only reason to spend mission credits on items you could buy would be to rotate the available mission rewards faster.  And you only want to do this if you have a *lot* of unused mission credits.  It's a gamble, just hoping that if you spend a small number of mission credits to clear one of the slots, that the next item to show up will be as book or mod you really want to buy.  Most of the time, it's a waste of credits, but every now and then, you could get lucky.

Baldr's response is spot on. Perfect advice.