Preferably free?

I use an application for computer based music called Reason to make sound effects using the virtual device rack and synths/samplers/etc.. I'd recommend it except that it's not free, and it took me a few years to get to where I could competently use it to create sound effect samples.

The alternative route that I began taking to circumvent the need for an application or person to make sounds was generating sounds from my own custom synth scripting language and building a synthesizing engine into my project that could parse the scripts and generate the PCM data to send to the audio hardware. This then still requires time be taken to craft the sounds via a scripting language, but it works. One could create a what-you-hear-is-what-you-get sort of editor for such a thing to speed up the creative process though.

If you're super desperate, one strategy would be to use existing sounds you can find but mix them together to create new samples using a free sound editing tool like Audacity, speeding them up or slowing them down, reversing some, low-pass or high-pass filtering certain sample contributions, etc..

But I've not yet found a good sound effect generating program that could help us all. Definitely a project for someone to look at, as goes for all art mediums that one would be inclined to improve upon the existing crafting tools for.

Sound effects isn't my field, I am mainly going for an all-in-one type deal, since I don't have the money to pay anyone to do stuff for me, so I have to do all of the programming/art/etc myself, which I am still a rookie at in all fields.

Check out :

FreeSound

for sound fx, you'll have to do the leg work and find them. They are licensed under the Creative Commons, so you can use them for free but there are limitations, attributions and maybe other limitations placed by the creators.

-ddn

If freesound doesn't lead to any hits try http://www.soundrangers.com/ and http://sounddogs.com/. Both offer an a la carte method where you can preview then purchase SFX and the prices, for the most part, are VERY reasonable. If these don't lead to something you can use or let's say there's one very specific sound effect you cannot seem to find then I'd suggest hiring a sound designer to create those specific sound needs.

Are we talking retro style sound or realistic, high fidelity sound?

Are we talking retro style sound or realistic, high fidelity sound?

I'm talking MK1 style sound.